LIBRARY OF CONGRESS, 



.$15 

UNITED STATES OF AMERICA. 



STEAM ENGINEERING. 

• • • 

EMBRACING 

IMPORTANT QUESTIONS ANSWERED 

CONCERNING THE 

STEAM ENGINE AND BOILER, 

BY A PRACTICAL ENGINEER OF LARGE EXPERIENCE. 

V^ 

THE COMBUSTION OF COAL 



AND ITS 

ECONOMICAL USE CONSIDERED. 



\ 



VAPORIZATION, EBULLITION, EVAPORATION, 

EXPANSION AND CONDENSATION OF WATER ; 

Etc., Etc. ^ 

== 
THIRD EDITION, REVISED AND ENLARGED. 



PUBLISHED BY 

HENRY S- WILLIAMS, 

65 Federal St., Boston, Mass. t 



/7* 3& 






Entered according to Act of Congress, in the Year 1892, 

BY 

HENRY S.. WILLIAMS, 
In the Office of the Librarian of Congress, at Washington, D. C. 

TT5? 



/ 1 V 



E. B. Stillings & Co., Printers. 



CONTENTS. 



PKRT I. 
IMPORTANT QUESTIONS ANSWERED 

CONCERNING THE 

Steam Engine and Boiler. . 



Section I. 


AIR 


Page 5 


II. 


Water 


" 7 


III. 


Fuel 


"13 


IY. 


Steam . . 


" 22 


" Y. 


Boilers . . 


" 26 


YI. 


Engines 


" 52 


" VII. 


Belts, Shafting, Speed 


" 62 




PK F2T II. 





COMBUSTION OF COAL. 

Section I. Combustion of Coal Chemicallt 
Considered ...... 

• " II. Combustion of Coal Practically 
Considered 



Page 



PH RT I I I. 



Section I. The Three States of Water 

II. Vaporization; What is Vapor? . 

" III. Vapor: an Elastic Fluid 

" IV. Heat and Expansion of Water 

" V. Heat Unit?; Vapor Atoms . 

" YI. Ebullition and Circulation 

" VII. Vapor in Water, Air and Steam 

" VIII. Evaporation — Escape of Vapor 

" IX. Condensation 

X. On the Vacuum ..... 



Page 103 
106 
113 
US 
125 
131 
136 
141 
147 
151 



APPENDIX. 

ELECTRICITY. 

Technical Terms . . . Page 155 

Parts of the Dynamo * . "159 

Miscellaneous Tables "164 



PREFACE. 



THEEE have been many works published on Steam 
and the Steam Engine, which, although treating 
the subject in a comprehensive and scientific manner, 
have, nevertheless, failed to accomplish that 'which was 
intended (the education of the engineer) , simply because 
the terms used by the college-educated writers, and sci- 
entific character of these books, are beyond the com- 
prehension of the great majority of the men who are 
expected to profit by their contents. 

In this little treatise all terms and tables not easily 
understood have been avoided, and in the simplest 
language possible the writer has briefly answered such 
questions as are likely to arise in the mind of an intelli- 
gent and practical engineer, using figures when necessary 
in their simplest form, and only such illustrations as 
will be readily under stood by any one with a common 
school education. 

Trusting that our efforts will be appreciated by those 
who desire to be qualified for the responsible position of 
an Engineer, but who find their opportunities limited for 
obtaining the requisite knowledge, this little Hand-Book 
is respectfully submitted by the Author. 



PKRT I. 
SECTION I, 



AIR. 



Question. What three elements of Nature must we 
understand to successfully master steam engineering? 

Answer. Air, water and fuel. 

Q. What is air composed of? 

A. Air is composed principally of the three gases — 
nitrogen, oxygen and carbonic acid gas, in the following 
proportions: nitrogen, four parts: oxygen, one part, 
with a slight admixture of carbonic acid gas. 

Q. Which is the most important of these gases? 

A. Oxygen is the most important, for to its agency 
are owing the existence of animal life, the maintenance 
of combustion, etc. 

Q. What is the atmospheric pressure or weight? 

X The atmosphere has a pressure or weight of just 
14.7 (H^) lbs. per square inch at the sea level. The 
higher we ascend in the air the less the pressure 
becomes. 

Q. What causes the water to rise in a pump? 

A. It is the displacement of air in the pump that 
causes the water to rise ; the same may be said in refer- 
ence to the siphon. 

Q. What is a vacuum? 

A. A space void of air. 

Q. If we had a vacuum formed in a vessel, and were 
to suddenly open a communication between it and the 
outside air, how fast would the air rush in? 

A. The air at its maximum density (14.7) is found to 
rush into a vacuum at the rate of from 1,300 to 1.100 feet 
per second. 

Q. Which is the best conductor of sound, damp air 
or dry air? 



6 KEY TO STEAM ENGINEERING. 

JL Damp air is said to be the best conductor of sound. 

Q. Is air a good conductor of heat and cold? 

A. We heat or cool a room by the circulation of air ; 
but air that is confined, or dead air, is a good non- 
conductor of either heat or cold. 

Q. Does water contain any air? 

A. There is about two per cent of air in ordinary 
fresh water; salt water contains less. 

Q. What is the weight of air? 

A. 13.817 (lS/o 1 ^) cubic feet of dry air at the sea 
level, with a temperature of 60° Fahr., weighs just one 
pound. 

Q. Will an ordinary air-pump remove all the air from 
a perfectly tight vessel? 

A. It will not remove quite all the air. 

Q. Can a vessel be filled with either water or steam 
without first leaving some means for the air to escape? 

A. The air must have a chance to escape as the ves- 
sel fills. 

Q. In what part of the vessel must the vent be left 
for the air to escape when it is being filled? 

A. At the top or highest point. 

Q. What effect on the density of air does the com- 
pressing of it have? 

A. If a volume of air were compressed into one-half 
of its space its density would be doubled, and if com- 
pressed into one-fourth of its space its density would be 
increased four-fold, and so on. 

Q. How much does air expand with heat? 

A. Air, at a constant pressure, expands T | T of its vol- 
ume for each (Fahr.) degree of heat communicated 
above zero. 

Q. If air is kept at a constant density, how many 
(Fahr.) degrees of heat will it take to double itself in 
volume? 

.1. Just4S0 c . 



KEY TO STEAM ENGINEERING. 



SKcrriON ii. 



WATER. 



Q. Of what is water composed? 

A. Water is composed of oxygen and hydrogen. 

Q. Is water compressible? 

A. Water is compressible and is perfectly elastic, but 
the change is so minute as to have no practical 
consequence. 

Q. How much pressure would be exerted at the bot- 
tom or base of a column of fresh water 27.71 (27^^) 
inches high? 

A. At a temperature of 62° Fahr., just one pound 
pressure ; and a column of fresh water at the same tem- 
perature 33.947 (33-^roo) feet high would have a pressure 
of one atmosphere or 14.7 lbs. per square inch at the 
base. 

Q. How high would a column of fresh water have to 
be to have a pressure of 15 lbs. per square inch at the 
base? 

A. A column of fresh water 34 feet high, at a tem- 
perature of 60° Fahr. 

Q. How much does water expand in freezing? 

A. It is said that water in freezing expands about y^-, 
or .083 of its volume. 

Q. What is the pressure at the base of a column of 
fresh water j at a temperature of 62 c Fahr., one foot 
high? 

A. Just .434 (x^o) of a pound. 

Q. What is the comparative weight of water? 

A, Water is just 13.6 (13-^) times lighter than mer- 
cury, and 815 times heavier than air at the sea level with 
a mean temperature (5Q° Fahr.) 



8 KEY TO STEAM ENGINEERING. 

Q. What is the weight of ice and snow? 

A. One cubic foot of ice at 32° Fahr. weighs just 57.5 
(57^) lbs., while one cubic foot of snow freshly fallen 
weighs 5.2 (5y%) lbs. and has twelve times the bulk of 
water. 

Q. What is the boiling point of fresh water? 

A. Fresh water would boil in a perfect vacuum at a 
temperature of 72° Fahr., in the open air at the sea level 
at 212° Fahr., and under a pressure of 15 lbs. per square 
inch at a temperature of 234° Fahr. 

Q. When is water at its greatest density? 

A. Water is the heaviest, or at its greatest density, at 
a temperature of about 39 c Fahr., or 4° Cent.; at this 
point it will expand either with the heat or the cold. 

Q. If the water expands both ways from the above 
temperature, then it must be evident that there is a point 
at either side of this temperature where the water has 
the same weight. What are these temperatures? 

A. Water at a temperature of 32° Fahr. has the same 
weight as water at 47° Fahr. 

Q. What is the weight of a cubic foot of fresh water 
at a temperature of 60° Fahr. ? 

A. Just 62.37 (62-^) lbs. 
. What is the weight of a U. S. standard gallon of 
fresh water at a temperature of 60° Fahr.? 

A. About 8.33 . (^iVo) lbs., consequently there are 
about 1\ gallons per cubic foot of water. 

Q. What is the weight of an Imperial gallon of fresh 
water at a temperature of 02° Fahr.? 

A. The Imperial gallon of fresh water weighs just 10 
lbs.., and it contains 277.274 (277- 1 - 1 i a -) cubic inches. 

Q. How many cubic inches does the U. S. standard 
gallon contain? 

A. Just 231 cubic inches, or 294 cylindrical inches. 

Q. How many cubic inches does a pound of fresh 
water contain at the mean temperature (56° Fahr.)? 



KEY TO STEAM ENGINEERING, 9 

A. About 28 cubic inches, or 35 cylindrical inches. 

Q. How many Imperial gallons per cubic foot of water ? 

A. Just 6.232 (G^o 3 ^) Imperial gallons. 

Q. How much will water expand in rising from 60 c 
Fahr. to 212° (boiling point)? 

A. About 2i per cent in volume. 

Q. How many volumes of steam at 212° (when it first 
rises from water) will one volume of water make? 

A. About 1,700 volumes of steam. 

Q. How many volumes of steam at 10 lbs, pressure 
(240° Fahr.) will one volume of water make? 

A, About 1,04-0 volumes of steam at 10 lbs., and about 
765 volumes at 20 lbs. pressure (about 260 c Fahr.), and 
so on. 

Q. About what is the average amount of salts con- 
tained in seas of the globe? 

A. It is said that the average amount of salts con- 
tained in seas of the globe is about 3J per cent; that is. 
if a box 6 feet deep were to be filled with the average sea 
Avater and evaporated or boiled away, there would remain 
about 2 inches of salt at the bottom. 

Q. "What portion of the earth's surface does the sea 
occupy ? 

^4. About f of the earth's surface. 

Q. What is the amount of curvature of one mile of 
the ocean's surface? 

.1. About 2.04 (2-5^) inches. 

Q. What would be the pressure per square inch of 
the water one mile below the surface of the ocean? 

A. It is estimated to be about one ton to the square 
inch. 

Q. How far below the surface of the ocean does the 
wave motion cease to be felt? 

A. About 3,500 feet ; and a few feet below the surface 
of the sea the water is of the same temperature all over 
the world. 



10 KEY TO STEAM ENGINEERING. 

Q. How does the friction of water in pipes increase? 

A. Friction of water in pipes increases as the square 
of the velocity; thus, if in one pipe the water is flowing 
at the rate of 2 feet per second and in another there is 
water flowing at the rate of 3 feet per second, the fric- 
tion in the latter will be more than doable that in the 
former : for the square oi 2 is 4, and the square of 3 is 9. 

Q. What are the four most notable temperatures for 
pure water? 

A. First • freezing point at the sea level, 32 c Fahr.; 
weight per cubic foot, 62.418 lbs. Second : point of maxi- 
mum density, 39.1° Fahr.; weight per cubic foot 02.425 
lbs. Third : British standard for specific gravity, 62° 
Fahr. ; weight per cubic foot, 62 355 lbs. Fourth : boil- 
ing point at sea level. 212° Fahr. ; weight per cubic foot, 
59.76 lbs. 

Q. What is the specific gravity of the average sea 
water ? 

A. About 1.028 (lrtfo")^ fresh water at the sea level 
with a mean temperature being taken as a standard or 
one. 

Q. What is the boiling point of the average sea 
water ? 

A. About 213.2° (213^) Fahr. ; and the weight of a 
cubic foot at a temperature of 62° Fahr. would be 64 
lbs. 

Q. What two ways does water hold substances of a 
foreign nature? 

A. Water holds foreign matter both in solution as 
well as in suspension. 

Q. Can this foreign matter be filtered from the water 
so as to thoroughly purify it? 

.1. The particles that are held in suspension can be 
filtered out ; but the matter held in solution cannot be sepa- 
rated except by evaporation, though a great portion 
can be separated by freezing the water to ice. 



KEY TO STEAM ENGINEERING. 11 

Q. What does Rossett consider the most probable 
temperature of water at its maximum density? 

A. About 4.107° (4-iVWr) Cent - or 30.35° (39-^%) Fahr. 

Q. Where does the water come from that supplies 
our principal rainfall (Atlantic States) ? 

A. From the Gulf and the Gulf Stream : the surface 
of this water being so much warmer than other waters 
that evaporation takes place quicker there. 

Q. What is the average rainfall of Boston and 
vicinity? 

A. About 48 inches per year; and 28 inches the mini- 
mum rainfall. 

Q. What is the yearly evaporation from a surface of 
water in the vicinity of Boston? 

A. From experiments made at Chestnut Hill reservoir 
by Mr. Desmond Fitz Gerald, it was found that the 
yearly evaporation averages about 35 inches. 

Q. What has the greatest specific heat, or heat- 
absorbing capacity? 

A. Water has the greatest specific heat, or heat- 
absorbing capacity (bromine and hydrogen excepted) . and 
is the unit of comparison employed for all measurements 
of the capacities for heat of all substances whatever. 

Q. What is the least possible pitch that will give 
motion to water? 

• A. It is said that an inclination or pitch of one inch 
in 15 miles would be sufficient to give motion to water if 
it were possible to construct such a plane. 

Q. What velocity in the average river would a pitch 
of 3 inches to the mile give? 

A. About 3 miles per hour; and a pitch of 3 feet to 
the mile would produce a torrent. 

Q. About what is the fall of the Hudson and Mississippi 
rivers? 



12 KEY TO STEAM ENGINEERING. 

A. According to the United States coast survey 
reports, the fall of the Hudson River from Albany to its 
mouth is only about 5 feet ; and the Mississippi River 
from its source at Lake Glazier to the Gulf of Mexico is 
] ,562 feet; from Cairo to the Gulf it is only 322 feet, the 
greater part of the fall being in its upper end. 

Q. What is the coldest body of fresh water known? 

A. Lake Superior is the coldest as well as the largest 
body of fresh water on the globe. 

Q. What do we know about water? 

A, Water is a liquid ; specific gravity, one or unity. It 
is formed by the chemical union of the two gases, hydro- 
gen and oxygen, in the proportion of two volumes of 
hydrogen to one of oxygen ; or, by weight, of one part of 
hydrogen to eight parts of oxygen. It exists, in nature, 
in the three states : solid, as ice or snow ; liquid, as 
water; gaseous, as fog or vapor. Water freezes at 32 : 
Fahr., and boils at 212° Fahr. at the sea level. Its great- 
est density is at about 39.2° Fahr.; from this point it 
expands both ways. It is the only single substance 
known that does not always expand with heat ; in freez- 
ing it is estimated that it expands from fa to fa in 
volume. It is the most powerful solvent known, as it 
dissolves minerals, vegetables and gases. On account of 
its solvent power, water is never obtained pure except 
when freshly distilled. The presence of salt in water 
raises the temperature of the boiling point, and lowers 
that of the freezing point. 



KEY TO STEAM ENGINEERING 13 



section: hi. 



FUEL. 



Q. How is heat derived? 

A. Heat is derived (artificially) in the most common 
form by the combining of the two gases, oxygen and 
hydrogen, with carbon, which is a solid. 

Q. What is it in the fuel that gives us heat? 

A. The two elementary bodies to which Ave owe the 
.eating power of all our fuels are carbon and hydrogen. 

Q. Which gives off the most heat? 

A, According to bulk carbon gives off the most heat, 
)ut according to weight hydrogen gives the most heat; 
for one pound of carbon, it is said, will heat 14,220 lbs. 
of water 1° Fahr., while one pound of hydrogen will 
heat 52,155 lbs, of water 1° Fahr. 

Q. Which will ignite first, carbon or hydrogen? 

A. Hydrogen will ignite first at a temperature of 
.about 300° Fahr., while carbon requires about 1.000° of 
heat to ignite it (a low red lustre), and even then burns 
very slowly. 

Q. What is the lowest possible temperature of a fur- 
nace when combustion is going on? 

A, Never less than 1,000° Fahr. 

Q. How much heat will the average match generate? 

A. Probably about 700° Fahr. 

Q. What is the standard instrument for measuring 
heat? 

A. The standard instrument for measuring heat in 
Britain and America is the Fahrenheit thermometer. Its 
boiling point is 212°, and its freezing point is 32 z : this 
makes just 180° between freezing and boiling points. 
For scientific purposes the French instrument is used 
nearly always. (This is the Celsicus, or more commonly 



14 KEY TO STEAM ENGINEERING. 

called the Centigrade.) The freezing point on this in- 
strument is 0°, and the boiling point is 100°, making just 
100° between freezing and boiling points. 

Q. How would you change a Cent, temperature to a 
Fahr. temperature? 

A. To change a Cent, temperature to a Fahr., simply 
multiply the Cent, temperature by § and add 32. Reverse 
the rule to change back ; thus, if we wish to change 100° 
Cent, to Fahr., we proceed thus: 100X|=180+32=212. 

Q. What is the substance used in an ordinary ther- 
mometer? 

A. The substance used in an ordinary thermometer is 
mercury. It is the heaviest of all liquids. It will expand 
■ggVo °f ^ ts volume for each Fahr. degree of heat applied, 
and it will freeze at a temperature of 37.8° (37- x \) below 
zero ; for colder temperatures alcohol is used, it being 
the hardest substance known to freeze (in its pure state) . 

Q. What will be the pressure at the base of a column 
of mercury 30 inches high? 

A. Just 15 lbs. per square inch. 

Q. What temperature does niercury boil at? 

A. Mercury boils at a temperature of 662° Fahr. For 
higher temperatures the use of the pyrometer is sub- 
stituted. In this instrument the heat is measured by the 
expansion of metals, and it is said that it will register 
correctly up to 7,000° Fahr. 

Q. Do all substances expand with heat? 

A. About all single substances do. 

Q. What would be the hardest substance of all to 
melt? 

A. Carbon would be the hardest substance of all to 
melt. 

Q. What is meant by a unit of heat? 

A. It is an amount of heat required to raise one pound 
of water oue decree Fahr. 



KEY TO STEAM ENGINEERING. 15 

Q. What is meant by combustion? 

A. Combustion is the term applied to the process of 
burning, which usually consists of the oxygen of the air 
uniting with the constituents of the combustible sub- 
stances. Thus the combustion of fuel is clue to the oxy- 
gen of the air passing into a state of chemical union with 
the carbon and hydrogen of the fuel, forming carbonic 
acid (C 2 ) and water vapor (H 2 0). 

Q. Does such chemical combination always generate 
heat? 

A. Yes, always. 

Q. Does the oxygen of the air have as much to do 
with combustion as carbon and hydrogen? 

A. Yes ; it is usually styled the supporter of combus- 
tion. 

Q. How much oxygen is necessary for the combustion 
of one pound of coal? 

A. 156 cubic feet of air must pass through the grate 
for every pound of coal consumed, and about one-fifth 
part of the air is oxygen. 

Q. What would be the effect of excess of air on com- 
bustion? 

A. The effect of excess of air on combustion, either 
with carbon or hydrogen as fuel, has been proven to have 
no effect on the quantity of heat produced where com- 
bustion was perfect; but the intensity of temperature 
will be diminished in any one place, for the fire covers a 
larger area according as the draft is increased. 

Q. What temperature does the phosphorus of a match 
inflame at? 

A. At 150° Fahr. ; so the mere friction of scratching 
the match generates heat enough to ignite it. 

Q. What temperature does the sulphur of the match 
ignite at? 

A. At about 500° Fahr. 



16 KEY TO STEAM ENGINEERING. 

Q. What temperature does wood ignite at? 

A. At about 800° Fahr. 

Q. What temperature does coal ignite at? 

A. Coal will ignite perfectly at 1,000° Fahr. 

Q. What temperature will kerosene oil freeze at? 

A. At from 10° to 12° below zero, Fahr. 

Q. What is the weight of one gallon of the crude 
petroleum? 

A. About 7.3 (7fo) lbs. 

Q. What is meant by latent heat? 

A. Latent or hidden heat is the heat that disappears in 
changing ice to water, or water to steam. This heat is 
not perceptible on the thermometer, for the thermometer 
only registers the sensible heat of bodies. 

Q. What substance will render latent the greatest 
amount of heat? 

A. Water, it is said. 

Q. What is the boiling point of fresh water? 

A. In a complete vacuum, at a temperature of 72° 
Fahr., under the ordinary atmospheric pressure at the 
sea level at a temperature of 212° Fahr., and. roughly 
speaking, for every 520 feet in height we ascend the 
boiling point will be reduced one degree. Water will 
boil only when it reaches a temperature of 234° Fahr. 
under a pressure of 15 lbs. per square inch. 

Q. How would the boiling point of other liquids be 
affected by a vacuum? 

A. In a complete vacuum liquids in general boil at a 
temperature of H0° Fahr. lower than in the open air. 

Q. What is the average rate of increased heat of the 
earth as we penetrate down below its surface? 

A. About one degree Fahr. for every (U feet in depth. 

Q. What is the relative value of some of the most 
common of our fuels? 



KEY TO STEAM ENGINEERING. 



17 



1 lb. Charcoal, pure, will raise 78 lbs. water from 32° to 212° Fahr. 
1 " " from wood, " 75 " 



" Wood, dried, 

" " undried, 

" Coal, bituminous, 

" Turf and Peat, 

" Alcohol, 

" Olive Oil, Wax, etc., 

" Ether, 

" Hydrogen, 



36 " 

27 " 

60 " 

25 to 30 " 

67i " 

90to95 " 

80 " 

236£ « 

Q. How many units of heat disappear in the con- 
version of one pound of boiling water into steam? 

A. It is estimated that there are about 1,004 Fahr. 
units of heat that disappear in the conversion of one 
pound of boiling water into steam, and yet the steam will 
only have the same amount of sensible heat as the water, 
for there is so much heat that disappears or becomes 
latent in changing water to steam. 

Q. How many cubic feet in the average ton of coal 
(2,000 lbs.)? 
A. Allow just 32 cubic feet per ton of average coal. 
Q. What will be the weight of air required to burn one 
pound of coal? 

A. It takes 32 parts by weight of oxygen to consume 
12 parts by weight of carbon. This is the proper pro- 
portion of each to produce carbonic acid gas, which we 
wish to do in order to generate the greatest amount of 
heat. It takes 4.35 lbs. of air to supply one pound of 
oxygen ; therefore, it will take 11.5 lbs. of air to provide 
the gas essential to the economical combustion of one 
pound of coal. 

Q How does wetting coal add to its fuel value? 
A. Heat resolves the moisture into steam, and finally 
into carbonic oxide and hydrogen. If the draught of air 
supplied to the fire is sufficient, both these gases will 
burn. The injection of steam will accomplish the same 
purpose. 

2 



18 KEY TO STEAM ENGINEERING. 

Q. What advantages arise from the use of petroleum 
as fuel, leaving the cost of the fuel out of the question? 

A. Fewer men at the fires, no smoke or soot, no 
ashes, fires can be kept more regular and are under better 
control, steam is more uniform. 

, Q. Setting aside the cheapness of petroleum, what 
advantages does it possess? 

A. The having absolutely perfect control over the 
fire, as well as its great cleanliness. 

Q. What is the theoretical evaporation due to the 
combustion of one pound of coal? 

A. Fifteen pounds of water from a temperature of 
212° Fahr. 

Q. What is the theoretical evaporation due to the 
combustion of one pound of petroleum? 

A. About twenty-two pounds of water, varying some- 
what with the kind of oil. 

Q. What is about the best practical value of one 
pound of coal ? 

A. From ten to eleven pounds of water. 

Q. What is the best practical value of one pound of 
petroleum? 

A. About eighteen pounds of water. 

Q. What proportion of the space occupied by one ton 
of coal would be required to stow an amount of petro- 
leum of equal total evaporative value? 

A. About three-eighths (f).of the space occupied by 
the ton of coal. 

Q. One ton of the average coal is equal to about how 
much wood for steaming purposes? 

A. About two cords of the average wood. 

Q. How many primary divisions can Ave -divide coal 
into? 

A. Two primary divisions, namely: anthracite, or 
hard coal, which does not flame when kindled ; and bitu- 
minous, or soft coal, which does. The reason is, the 



KEY TO STEAM ENGINEERING. 19 

soft coal contains so much more hydrogen and ignites at 
so low a temperature, that it flames the instant it 
touches a hot fire. 

Q. How much carbon does anthracite coal contain? 

A. Anthracite sometimes contains as much as 94 per 
cent of carbon ; and as this element decreases in amount, 
it graduates into a bituminous coal. The term ' ' anthra- 
cite " is never applied to coal containing less than 80 per 
cent of carbon. 

Q. How many varieties does bituminous coal contain? 

A. Bituminous coal includes almost an endless num- 
ber of varieties, one of the costliest being cannel coal. 
Cannel coal contains more gas than any other ; in fact, 
it contains from 8,000 to 15,000 cubic feet per ton. 

Q. What does a ton of average coal contain? 

A. It is said that a ton of coal contains, besides the 
gas, 1,500 lbs. of coke, 20 gallons of ammonia water and 
140 lbs. of coal tar. 

Q. In using coal, what portion of it burns on the 
grate ? 

A. Fifty to 67 per cent of carbon (which is the solid 
part) burns on the grate, while 20 to 32 per cent of 
carbon and hydrogen (the gas) has to burn in the open 
space above and back of the fuel, or escape unconsumed. 

Q. How much gas will be required to generate as 
much heat as the average coal per ton? 

A. The heating power of one ton of the average coal 
is equal to 40,000 cubic feet of gas. 

Q. How much water will a pound of coal evaporate? 

A. It takes about one pound of the average coal to 
evaporate one gallon of fresh water in the average boiler. 

Q. What is the maximum consumption of coal per 
square foot in steam boilers? 

A. The consumption of coal for steam boilers cannot 
exceed (with natural draught) 12 lbs. per hour for each 
square foot of grate surface. 



20 KEY TO STEAM ENGINEERING. 

Q. How do we measure the value of fuels? 

A. The value of any fuel is measured by the number 
of heat units which its combustion will generate. The 
fuel used in generating steam is composed of carbon and 
hydrogen and ash, with sometimes small quantities of 
other substances not materially affecting its value. ' ' Com- 
bustible " is that portion which will burn ; the ash or 
residue varying from 2 to 36 per cent in different fuels. 

Q. How many sources of waste are there in fuels? 

A. There are two sources of waste in fuels burned 
under steam boilers. The gases going to waste to the 
chimney carry off on an average 31 per cent of fuel, and 
in the most economical boilers this cannot be reduced 
below 12 per cent ; then the feed water has to be heated 
from the normal temperature to that of the steam before 
evaporation can commence, and this generally at the ex- 
pense of the fuel which should be utilized in making 
steam. 

Q. What can we say in regard to petroleum as fuel? 

A. Crude petroleum is, without doubt, the coming fuel 
on locomotives and ocean steamers ; for less than one- 
half the room formerly used for coal will be required to 
store the oil, while the weight will not be quite one-half. 
Three barrels of oil of 42 gallons each slightly exceeds 
the heating capacity of a ton of average coal. The oil 
weighs 913J lbs. and may be purchased at a saving of 
about 50 per cent, it is said. 

Q. Is there any fuel that would be cleaner than oil to 
handle? 

A. Gas is the only fuel that would be cleaner. 

Q. How much air will be required to burn one pound 
of coke? 

A. One hundred and fifty-six cubic feet of air is 
required to pass through the grates to burn one pound 
of average coal; and coke, it is said, requires one-third 
more. 



KEY TO STEAM ENGINEERING. 21 

Q. Which is the best, cold or hot air for a boiler 
furnace? 

A. The coldest air, if thoroughly mixed on its 
entrance with the fuel or gases, will never cool, but will 
always sustain or increase the heat of the furnace. Air 
in bulk only can do any harm; and this is objectionable 
from the obstruction which it forms to combustion, as 
well as from its abstraction of heat from the furnace. 
Thus, the air, divided into thin streams, should be taken 
from the outside of the boiler directly into the furnace 
through very small holes or openings. 



22 KEY TO STEAM ENGINEERING, 



SECTION IV. 



STEAM. 



Q. What is steam? 

A. Steam is an elastic fluid generated by the action of 
heat upon water. 

Q. What is steam composed of ? 

A. The vapor arising from water at or above its 
boiling-point, called " steam," is a chemical compound 
consisting of eight parts by weight of oxygen and one 
part of hydrogen. Steam proper is perfectly transpar- 
ent and colorless, dry, and only moist when condensed, 
wholly invisible, and when apparent, only so by reason 
of partial condensation. 

Q. What is the weight of steam? 

A. 26 36 v 26 iVo) cubic feet of steam at the atmos- 
pheric pressure weighs just one pound (avoirdupois) ; or 
5 cubic feet of steam at 75 lbs. pressure to the square 
inch (gauge pressure) weighs about one pound. 

Q. What is meant by low pressure steam? 

A. Low pressure steam is steam not exceeding 15 
lbs. per square inch. 

Q. What is meant by superheated steam? 

A. Superheated steam is steam which has a greater 
temperature than that due to its pressure; that is, heat 
is applied to the steam pipes or vessel containing steam 
after it has left the water from which it was generated. 

Q. Does the pressure of steam increase as the tem- 
perature? 



KEY TO STEAM ENGINEERING. 23 

A. The pressure of steam increases at a far higher 
rate than the temperature ; doubling the temperature 
increases the pressure nearly twenty-three times. 

Q. How do we find the latent heat of steam? 

^4. The latent heat of steam is generally found by 
subtracting its sensible heat from 1,202 ; at 45 pounds it 
will be exactly right, for at that pressure the total heat 
will be just 1,202° Fahr. 

Q. Does steam or vapor rise from water at all tem- 
peratures? 

A. It does. 

Q. Is there any difference between steam and vapor? 

A. The chemical analysis shows no difference, but the 
different authorities generally consider them different ; 
for, usually speaking, steam is formed artificially, while 
vapor is formed naturally ; and another difference is the 
temperature — anything less than 212° Fahr. is styled 
vapor, and over that it would be called steam. 

Q. Is there any rule for the amount of steam pipe 
required to heat a building with steam? 

^4. The " Master Steam Fitter" gives three rules, as 
follows, but I consider the third one the most practicable : 

1st. One square foot of steam pipe for every 6 square 
feet of glass in the windows. 

2d. One square foot of steam pipe for every 400 square 
feet of wall and ceiling. 

3d. One square foot of steam pipe for every 80 cubic 
feet of space to be heated. 

In heating a room with hot water a larger surface to ra- 
diate from is needed, on account of its lower temperature. 

Q. Suppose we have seven stores to heat with steam, 
whose dimensions are each 100 feet long, 30 feet wide 
and 15 feet high. How many square feet of steam will 
be required to heat thera, and how many running feet of 
1-inch pipe will it take, the 1-inch pipe being about 4 
inches in circumference ? 



24 KEY TO STEAM ENGINEERING. 

A . Figure thus : 

100 ft. length of each store. 
15 ft. height " 

500 
100 

1500 
30 ft. width of each store. 

45000 cubic ft. of space in one store. 
No. cubic ft. 1 7 *™iber of stores. 

of steVm nipe \ 80 ) 315000 CUDic ft - of s P ace in tne 7 stores. 

will heat. J 393T _|_ No gq ft gt , m pipe req , d tQ neat 7 stores> 

3 ft. the length of 1-inch pipe required to get 1 

sq. ft. h t'g surface from, as proven below. 

1 1811 ft. length of 1-inch pipe to heat the 7 stores. 
Circumf . of a 1-inch pipe 4)144 sq. inches to 1 sq. ft. 

36 = 3 ft. length of 1-inch pipe to get 
1 sq. ft. of heating surface in. 

Q. How does steam absorb what is called "latent" heat? 

A. When steam is generated in a boiler the water is 
heated until it arrives at the boiling-point (212° Fahr.) ; 
and if the vessel is an open one, the temperature cannot 
be raised any higher. But if we wish to convert all the 
water into steam, we will have to add a great deal more 
heat, and this is the heat that disappears, or latent heat 
as it is called; for the steam rising from boiling water 
in an open vessel is of the same temperature as the water, 
sensibly, but still we know it contains a great deal more 
heat than the water (sensible and latent heat combined). 

Q. How much lighter is steam at 212° Fahr. than air? 

A. Steam at 212° Fahr. is not quite one-half as heavy 
as air, the specific gravity of air being 1.0000 and that of 
steam at 212° Fahr. but .4883 (■$$?„-). 

Q. In running an engine, which is the most economi- 
cal, high or low pressure steam? 

A. High pressure steam is the most economical, be- 
cause we have a greater expansion force to profit by. 

Q. In heating a building, which is the most economi- 
cal, high or low pressure steam? 



KEY TO STEAM ENGINEERING. 25 

A. Low pressure steam ; for the relative volume of 
steam decreases faster than the temperature increases, 
as the pressure rises. 

Q. What is meant by the relative volume of steam? 

A. It is the proportional amount of steam that a 
certain amount of water will produce. 

Q. Give a table of the relative volume of steam at 

different pressures ; also the temperatures. 

Steam. Temperature in Fahr. Relative volume. 

1700 
1040 
903 
765 
677 
608 
552 
506 
467 
434 
406 
381 
359 
340 
323 
307 
293 
281 
269 
259 
249 
239 
231 
223 
216 
209 
203 
197 
191 
186 





212° 


10 lbs. per sq. inch. 


240° 


15 " " 


250° 


20 " " 


260° 


25 " " 


267° 


30 " 


274° 


35 " " 


281 ° 


40 " " 


287° 


45 « u 


293° 


50 " " 


298° 


55 " " 


303° 


60 " 


308° 


65 " '« 


312° 


70 " " 


316° 


75 " " " • 


320° 


80 " " 


324° 


85 " " 


328° 


90 " " 


332° 


95 " " 


335° 


100 « " 


338° 


105 " " 


341° 


110 k ' " " 


344° 


115 " " 


347° 


120 " " 


350° 


125 "• " 


353° 


130 " " 


356° 


135 " " 


358° 


140 " " «« 


360° 


145 " " " 


363 c 


150 " " 


365° 



26 KEY TO STEAM ENGINEERING. 

SECTION V. 



BOILERS. 

Q. What is a steam boiler? 

A. The boiler is the vessel in which steam is gener- 
ated, to furnish motive power for the steam engine. 

Q. What are some of the most common boilers used? 

A. The horizontal return tubular boiler, the horizon- 
tal return flue boiler, the upright tubular boiler, the 
locomotive style of a boiler, and the safety or sectional 
boiler. 

Q. Which is the most common boiler used? 

A. The horizontal return tubular boiler is the most 
common one used; and it is the best when we take into 
consideration the first cost, repairs, economy of fuel, the 
ease with which it can be cleaned, the length of time it 
will last, and the ease with which it can be handled. 

Q. What is the furnace? 

A. It is the space above the grate where the fire lies. 

Q. What is the ash-pit? 

^4. It is the space below the grate. 

Q. What is the bridge wall? 

A. It is the wall at the back end of the grate in the 
return tubular or flue boilers. 

Q. What is the use of the bridge wall? 

A. It keeps the coal from falling off the rear end of 
the grate. It also forces the flame up to the bottom of 
the boiler ; and, probably the most important of all, 
when the doors are opened to put on fresh fuel it re- 
duces the amount of cold air that will be drawn out 
under the boiler back through the tubes or flues and up 
the chimney. 

Q. What is the combustion chamber? 

A. It is the space back of the bridge wall. 

Q. What is the blow-oft" pipe? 



KEY TO STEAM ENGINEERING. 27 

A. It is a pipe put in at the bottom or lowest part of 
the boiler for emptying the boiler when necessary, or to 
open occasionally to blow out the sediment that may 
accumulate. 

Q. What is the mAi-hole in a boiler? 

A. It is an opening for a person to enter the boiler to 
inspect or repair it. 

Q. What are the brackets on a boiler? 

A. They are the castings riveted to the sides of a 
boiler for holding it up on the brick work. 

Q. What are the stays in a boiler? 

A. The braces for holding the flat places from bulging 
out. 

Q. What are the hand-holes in a boiler? 

A. Small openings for cleaning or inspecting the boiler. 

Q. What is the safety plug in a boiler? 

A. It is a plug of metal that will fuse at a low tem- 
perature, placed at the low water line in a boiler. 

Q. What is the use of the safety plug? 

A. If the water should be allowed to get down as low 
as the safety plug, it is pretty apt to melt out and put 
out the fires ; and, if it works properly, the boiler could 
not explode from low water. But, of course, there are 
several reasons why it could not always be depended 
upon ; and it is not every boiler that has one. 

Q. What is meant by the heating surface (H. S.) in a 
boiler? 

A. The H.S. of a boiler is that portion exposed to the 
fire, and, of course, it must be always covered with water. 

Q. How many square feet of H. S. will it take to 
equal one horse power (H. P.) ? 

A. In our best boilers, which are the horizontal return 
tubular, we allow 15 square feet of H. S. per H. P. 

Q. What will be the H. P. of a boiler of the following 
dimensions : 18 feet long, 5 feet diameter, with 74 tubes 
that are each 3 inches in diameter? (This boiler is of the 



"€8 KEY TO STEAM ENGINEERING. 

horizontal return tubular pattern, and we will suppose 
the H. S. of the shell to include one-half of the circum- 
ference of the boiler.) 
A. Proceed thus : 

3.1416 decimal number to get circumf. from diam. 
5 ft. diameter of the boiler. 



2)15.7080 ft. circumference of the boiler. 

7.854 ft. \ circumference of the boiler. 
18 ft. length of the boiler. 



62832 

7854 



141.372 sq. ft. of H. S. in the shel< of the boiler. 
1046.1528 " " " " 74 tubes of the boiler. 



H^lfper \ 15 > 1187 - 5248 " " " " whole boiler. 



H. P. 



79.1683 H. P. of a boiler of the above dimensions, 
but it is so near 80 that we would call it 
an 80-H. P. boiler. 

3.1416 decimal number to get circumf. from diam. 
3 inches diameter of each tube. 



Inches per ft. 12)9.4248 inches circumference of each tube. 

.7854 ft. 

18 ft. length of each tube. 



62832 

7854 



14.1372 sq. ft. H. S. in 1 tube. 

74 number of tubes in the boiler. 



565488 
989604 

1046.1528 sq. ft. of H. S. in the 74 tubes. 

Q. How do we find the safe working pressure (S. W. 
P.) of a boiler? 

A. The rule that the United States inspectors and the 
insurance inspectors use is : Take the tensile strength 
of the boiler plates and divide it by 6, multiply this quo- 
tient by th£ thickness of the plate in fractional parts of an 
inch, then take this product and divide it by the radius of 
the boiler in inches ; this quotient will be the S. W. P. of 
a single-riveted boiler, if reasonably new. If the boiler is 
double-riveted, 20 per ct. can be added to the above result. 



KEY TO STEAM ENGINEERING. 29- 

Q. "What is meant by the tensile strength? 

A. The strength required to tear asunder a piece of 
metal whose cross sectional area will be equal to one 
square inch. Take, for example, a piece of metal one- 
half of an inch thick and 2 inches wide, or a piece one- 
fourth of an inch thick and 4 inches wide, will have a 
cross sectional area of 1 square inch. 

Q. What is meant by the radius of a boiler? 

A. One-half of the diameter is the radius. 

Q. Get the S. W. P. of a boiler whose tensile strength 
is 40,000 lbs., thickness of plate one-fourth of an inch, 
and diameter of shell 54 inches. 

A. Proceed thus : 
Constant 6)40000 lbs. tensile strength of the iron. 

6666 
.25= )£ of an inch, thickness of the iron. 



33330 
13332 

Radius of ) 

boiler [ 27)1686.50(61.7=61^ lbs., the S. W. P. of the boiler if 
in inches, ) 162 single-riveted and in good 

condition. 

46 



195 

189 



Q. If the tensile strength of a boiler was not known, 
how would we get the S. W. P.? 

A. Por an iron boiler we would take 40,000 lbs. as a 
tensile strength, because that is the lowest strength of 
iron used in the construction of boilers (50,000 lbs. is 
the highest). Por a steel boiler we would use 50,000 lbs. 
of tensile strength, because that is the lowest tensile 
strength of steel used in the construction of boilers 
(65,000 lbs. is about the highest). 

Q. What proportion of the strength of the whole 
boiler plate is the strength of a single-riveted joint? 



30 KEY TO STEAM ENGINEERING. 



56 per cent of the strength of the whole plate. 



What is the strength of a double-riveted joint? 
70 per cent as strong as the whole plate. 
What is the strength of a triple-riveted joint? 
82 per cent as strong as the whole plate. 
How should an ordinary return tubular boiler be set? 
On a good, firm foundation, so that it will not 
settle in any way; and it is a good plan to set the rear 
end a little low, say from one-half to three-quarters of 
an inch for an ordinary length boiler (14 to 18 feet). 

Q. What is the best length for grate bars in an 
ordinary horizontal return tubular or flue boiler? 

A. From 4 to 5 ft. in length gives about the best results. 

Q. Can we reckon the H. P. of a boiler by the number 
of square feet of grate surface (Gt. S.) it contains? 

A. Yes ; for each square foot of Gt. S. in our modern 
return tubular boilers will be equal to 3 H. P. ; and each 
square foot of Gt. S. in the locomotive style of a boiler, 
or the upright tubular boiler, will be equal to 4 H. P. 
These rules apply to boilers where natural draught alone 
is depended upon for the combustion of the fuel. 

Q. How do we find out how many square feet of 
Gt. S. there should be under a boiler? 

A. In our best modern boilers (horizontal return 
tubular) the diameter of the boiler in feet multiplied by 
itself will equal the Gt. S. in square feet; or, divide the 
H. P. of the boiler by 3, the quotient will equal the Gt. S. 
And still another way is, to divide the H. S. by 45; the 
quotient will equal the Gt. S. in square feet. 

Q. How is the quickest way to find out the number of 
square feet of H. S. in a boiler? 

^4. Multiply the number of square feet of .Gt. S. by 
45 ; the product will equal the H. S. nearly. 

Q. How much area of space do Ave leave over the 
bridge Avail under a return tubular or flue boiler? 

.1. 18 square inches of space per H. P. of the boiler. 



.KEY TO STEAM ENGINEERING. 31 

Q. What should be the total area of the flues or 
tubes in a boiler? 

A. The total area of the flues or tubes in a boiler is 
from one-fifth to one-seventh the area of the grate. 

Q. What should be the area of a chimney for a 

boiler ? 

A. From one-seventh to one-tenth the area of the 

grate. 

Q. In putting a fire under a boiler where everything 
is cold, is there any danger of heating up too quickly? 

A. There is, for there will be an unequal expansion ; 
and we do not want to bring the change about too quickly, 
for there would be more danger of injuring the boiler in 
so doing. 

Q. If we were going to clean a boiler that was set in 
brick-work, what is the most important thing to look 

after? 

A. Do not blow the water off till the brick-work has 
had time to cool off some. For an ordinary boiler, let it 
stand with the dampers open for at least 4 or 5 hours 
after the fire has been all drawn out before letting the 
water off. 

Q. Why should leaks be stopped as soon as possible? 

A. The principal reason is on account of the loss of 
steam that takes place, then the wearing away of the 
parts that come in contact with the leak, and the sound 
of escaping steam which is very disagreeable to the ear. 

Q. How near the under side of the boiler should the 
grate bars be, to give the best results? 

A. Grate bars should be about 24 inches below the 
lowest part of the boiler for burning anthracite coal, or 
any fuel that does not contain a large proportion of 
volatile matter (smoky substance).- When soft coal is 
used, from 27 to 30 inches is found to give the best 

results. 

Q. What is the most important fixture on a steam 

boiler? 



32 KEY TO STEAM ENGINEERING. 

A. The safety-valve ; for, when it is in good working 
order (if it is of sufficient size), there will be no possi- 
bility of getting an over-pressure of steam. 

Q. What is the rule for getting the size of a safety- 
valve ? 

A. One-fifth of the H. P. of the boiler will equal the 
area of the safety-valve in square inches, or the Gt. S. 
multiplied by .5 to .8 (iVto A)- Use tne larger fraction 
for the self-contained fire-box boilers, as the locomotive 
style, and the upright boilers. 

Q. What is the greatest danger that can happen to a 
safety-valve ? 

A. Getting corroded, or stuck down, or overloaded. 

Q. Will a safety-valve close at the same pressure that 
it opens? 

A. No; for there is a little more surface exposed to 
the steam when it is open; usually there is about 3 lbs. 
difference between opening and closing points. 

Q. How do we keep a . safety-valve in good working 
order ? 

A. A safety-valve should be tried at least once every 
day in the following manner : Let the steam run up to 
the blowing point and see if the valve opens promptly. 
If it does, it shows that the valve is all right, and all we 
have to do is to speed up the pump, or close the dampers 
to put the steam down so there will not be too much 
steam lost. If the valve does not start itself, then it 
will have to be raised by hand carefully. 

Q. What is the rule for the size of a safety-valve that 
the Board of Trade uses? 

A. For return tubular boilers the Board of Trade 
allows one-half of a square inch area of safety-valve for 
each square foot of grate surface. 

Q. What rule do the insurance inspectors of this 
country use for size of safety-valves? 



KEY TO STEAM ENGINEERING. 33 

A. They give for a pop, or spring-valve, 1 square inch 
area for every 3 square feet of grate surface ; and for a 
common valve, 1 square inch area for every 2 square feet 
of grate surface. 

Q. How clo we get the number of square inches in a 
safety-valve? 

A. Multiply the diameter of the valve in inches by 
itself, then multiply the product thus obtained by .7854 
(tVoVo) 5 tn ^ s l ast Product will be the square inches that 
the valve contains. 

Q. Hoav clo we get the total pressure on a safety-valve ? 

A. Multiply the weight on the lever in pounds by the 
distance in inches that it sets from the stud or fulcrum, 
and divide the product by the distance in inches from 
the center of the stud or fulcrum to the center of the 
valve stem, in line with the lever ; this quotient will be 
the total pressure on the valve. Now divide the total 
pressure on the valve by the number of square inches 
area in the valve, and the quotient will be the pressure 
per square inch on the boiler, or " gauge pressure," as it 
is called. 

Q. How clo we get the length of the lever of a safety- 
valve ? 

A. Take the total pressure on the valve and multiply 
it by the distance in inches from center of stud to center 
of valve stem ; now divide this product by the weight 
of the ball in pounds ; the quotient thus obtained will be 
the distance in inches from the center of the weight on 
lever to the center of the stud or fulcrum, or " the length 
of the lever," as it is called. 

Q. How clo we find the weight of the ball on a safety- 
valve? 

A. Take the total pressure on the valve and multiply 
it by the distance in inches from the center of the stuc? 
or fulcrum to the center of the valve stem in line with 
the lever ; now divide this product by the length of the 



34 KEY TO STEAM ENGINEERING. 

lever in inches (from center of stud or fulcrum to center 
of weight on lever) ; the quotient thus obtained will be 
the weight of the ball in pounds. 

Q. How are spring, or pop, safety-valves adjusted? 

A. Spring-valves, or what are usually called ''pop- 
valves," are adjusted by a test gauge, and are usually 
locked up, so the engineer cannot tamper with them. 
When they are not locked up I consider them a danger- 
ous valve. 

Q. What will be the total pressure on a safety valve 
of the following dimensions : Valve, 3 inches in diame- 
ter ; weight or ball, 105 lbs.; distance from center of 
ball on lever to center of stud, 20 inches, and distance 
from center of stud or fulcrum to center of valve stem 
(in line of lever), 3 inches? 

A. Proceed thus : 

3 inches, diameter of valve. 
3 inches " " " 

9 circular inches, area of valve. 

.7854 



7.0686 square inches, area of valve. 
105 lbs., weight of ball. 
20 inches, length of lever. 



Distance from ) 3^910^ 



stud to valve, j 

700 lbs., total pressure on the valve. 
?q- i* 1 -, area ) 7>0686 )7 00<0 000(99. lbs. pressure per sq. in. on boiler 
in me vaive, ) 636174 when valve opens. 



638260 
636174 



2086 

Q. What will be the length of lever of the above 
valve? 

A. Proceed thus : 

700 lbs., total pressure on the valve. 
3 in. distance from stud to valve stem. 

Weight of the ball, 105)2100(20 hi., length of lever from stud to weight. 
210 



KEY TO STEAM ENGINEERING. 35 

Q. What will be the weight of the ball of the above 

valve? 

A. Proceed thus : 

TOO lbs., total pressure on the valve. 
3 in. dist'ce from center of stud to center of valve stem. 

Length ) 

of [ 20)2100(105 lbs., the weight of the ball, 
lever, ) 20 

100 
100 

Q. How do we prove a safety-valve? 

A. We can prove it by means of the above figures, or 
by means of the steam gauge; for, of course, the steam 
gauge and safety-valve must always prove each other. 

Q. What must we observe in relation to the steam 
gauge? 

A. The steam gauge must stand at zero when the 
pressure is off, and it should show the same pressure 
as the safety-valve is set to blow at when the safety- 
valve blows. 

Q. What means do we have of knowing the height of 
the water in a boiler? 

A. The most common contrivances used are the water 
glass and gauge cocks. The latter is considered the 
most reliable : but I think any intelligent person will 
choose the water glass. 

Q. How can we tell if the glass is all clear and right? 

A. By the motion of water in the glass, by the blow- 
off, or by means of the feed pump. 

Q. Which end of the water glass is the most liable to 
get clogged up ? 

A. The lower end of the glass is the most liable to 
get clogged up with mud. It is the same with the lower 
gauge cocks. 

Q. If the water glass breaks, what should we do? 

A. Close the valve in the lower end of the glass first; 
then, when that is done, close the upper one. In this 
way a person is not very apt to get burned. ' 



36 KEY TO STEAM ENGINEERING. 

Q. How much space will one horse-power of a boiler 
heat? 

A. One horse-power of a boiler is sufficient to heat 
40,000 cubic feet of space. 

Q. How do we get the pressure on stay-bolts in a 
boiler? 

A. To get the pressure on stay-bolts in a boiler where 
they are set in squares (as in the fire-box of a locomotive 
or portable boiler) , simply multiply the distance between 
stays, center to center, by itself; this equals the number 
of square inches area that each stay has to support, 
minus the area of one stay. Now multiply this by the 
boiler pressure ; this will equal the pressure on each stay. 

Q. Suppose in a locomotive boiler the stays in the 
lire-box are 1 inch in diameter and 5 inches apart 
(center to center), with a boiler pressure of 130 lbs. to 
the square inch; what will be the pressure on each stay? 

A. Proceed thus : 

5 in. apart, center to center. 
5 " " " " " 

25 sq. in. in area, area of 1 stay. 
.7854 sq. in., area of 1 stay. 



24.2146 sq. in., area 1 stay supports. 
130 lbs. pressure per sq. in. 



7264380 
242146 



3147.8980 lbs., pressure 1 stay has to support. 
1 in., diam. of stays. 
1 " " " 

1 
.7854 times square of diameter in inches. 

.7854 sq. in., area of -stay. 

Q. How much pressure per square inch will these 
stays stand with safety? 

A. The material used in the construction of these 
stays will safely stand 5,000 lbs. per square inch of cross 
sectional area. 



KEY TO STEAM ENGINEERING. 37 

Q. What is the consumption of water per H. P. of a 
boiler? 

A Each nominal H. P. of a boiler requires one-half of 
a cubic foot (about 30 lbs.) of water per hour. 

Q. What is the evaporation of water per pound of 
coal in boilers? 

A. From 7 to 10 lbs. of water per pound of average 
coal. Take the average boiler, and the evaporation will 
be a gallon (8J- lbs.) of water to a pound of coal. 

Q. What is the best substance to put in a boiler to 
keep it clean? 

A. Soda is one of the best as well as one of the 
cheapest substances for keeping a boiler clean, and it is 
recommended by the inspectors. 

Q. How is the soda used in a boiler? 

A. If a boiler is very dirty, dissolve and pump in 
from one to three pounds per day ; blow off some water 
every morning before the fire has been started ; let the 
boiler down and clean often. If a boiler is clean and 
the water used good, a couple of pounds per week will 
be sufficient. 

Q. Where should the blow-off be attached to a boiler? 

A. All boilers should have both a surface blow-off, 
and one at the bottom or lowest part of the boiler ; the 
surface blow-off to be used while running, for the water 
is then in motion ; the lower one to be used in the 
morning, or at such time as the water has been at rest 
long enough for the sediment to settle to the bottom. 

Q. How much more heat will be required to heat 
through ordinary boiler scale than iron of the same 
thickness? 

A. The heat-conducting power of ordinary boiler scale 
compared with that of iron is as 37 to 1 ; or, taking it in 
another way, scale ^V of an inch thick over the H. S. of 
a boiler will require an expenditure of 15 per cent more 
fuel than if the same boiler was clean. 



38 KEY TO STEAM ENGINEERING. 

Q. Give proportions of riveted joints or seams in a 
boiler. 

A. 

Double-riveted. Single-riveted. 

Thickness of plate, 1.0 1.0 

Diameter of rivet, 1.7 1.7 

Breadth of lap, 8.3 5.4 

Pitch of rivet in line, 7.1 4.6 

Distance apart of pitch lines, 2.8 

Distance from edge of plate, 2.7 

Q. What gives us draught in a chimney? 

J.. Other things being equal, the action of a chimney 
depends upon its perpendicular height and the difference 
in temperature within and without the chimney. 

Q. How do we get the best results from a chimney? 

A. To get the best results from a chimney, let every 
particle of air that enters it pass through the grates. 

Q. What kind of a chimney gives the best draught? 

A. Brick chimneys are better than iron, for the 
upward current of gases does not get cooled off so much ; 
and round chimneys are better than square ones, for the 
gases ascend in a spiral motion. 

Q. Would there be any harm if water came in contact 
with the exterior of a boiler? 

A. Yes ; look out that there are no leaks in the boiler 
or roof which might cause the exterior of the boiler to 
get wet ; for corrosion is sure to take place in a short 
time, if such places are not looked after. 

Q. Give good modern proportions of a 96-H.P. boiler 
of the return tubular pattern. 

A. 18 feet, length of the boiler. 
6 feet, diameter of the boiler. 
1.440 square feet of H. S. in the whole boiler. 
1,260 " " " " tubes of the boiler. 

180 " " " " shell 

l .)0 tubes in the boiler, each 3 inches in diameter. 



KEY TO STEAM ENGINEERING. 39 

32 square feet of Gt. S. in the grate. 
12J " area over the bridge wall under boiler. 

4 " "of the chimney. 

380 lbs. of coal, maximum hourly consumption. 
410 gallons of water " " " 

80 lbs. of steam, blowing point of safety-valve. 
75 " " maximum pressure run. 

90 " " S.W.P.of the boiler (single-riveted). 

46,900 lbs., the tensile strength of the iron. 
-gf of an inch, the thickness of the iron. 
16 inches, area of the safety-valve. 
4J inches, diameter of the safety-valve. 
Q. What about water-glasses and gauge cocks? 
A. Water-glasses and gauge-cocks should be kept clean, 
both within and without. They should be frequently 
blown out to make sure the passages are all clear. 
Q. What about a water column? 

A. When a water column or combination is used it 
should be frequently blown out to make sure that it does 
not get stopped up with mud or scale. It is the water 
passages where trouble is liable to arise. 

Q. What is the fusible plug used for in a steam boiler? 
A. The fusible or safety plug is an extra precaution 
in a boiler, as a guard against low water. 

Q. What is the composition and melting points of the 
ordinary safety plug? 
A. 



Ti 


q, 6 parts. Le 


ad, 1 p 


art. 






Me 


Its at 381° 


Fahr. 




' o 


" ' 


1 


" 








" 378° 


" 




' 4 


" « 


1 










" 365° 


" 




3 


" 


1 


" 








" 35(5° 


" 




' 2 


" ' 


1 


" 








" 340° 


" 




H 


'.« < 


1 










• ; 334° 


" 




4~ 


' 


4 




Bisi 


t uth 


1 pait. 


•' 320° 


" 




' 3 


' 


3 




' 




1 " 


" 310° 


" 




' 2 
' I 


:: 


2 
I 








1 " 
1 " 


" 292° 
•• 254° 


i« 




' 3 


. " • 


' 5 








8 " 


" 212° 


" 




' 19 


" • 


31 








50 " 


" 212° 


" 




1 


* 


1 


" 






2 " 


" 201° 


*< 




' 2 


" * 


3 


4 


'• 




5 " 


" 199° 


" 


Zi 


ic,33.3 


parts. ' 


33.3 


part 


9. " 




33 4 parts. 


" 200° 


" 



40 KEY TO STEAM ENGINEERING. 

Q. If we were going to select a composition for a 
fusible plug in a boiler of which the highest steam pres- 
sure to be run is 60 lbs., how should we choose one? 

A. By referring to our table of temperatures of 
steam, Ave find that 60 lbs. of steam has a temperature of 
308° Fahr. ; and on looking at our table of alloys for 
fusible plugs, we find that a composition of 3 parts of 
tin, 3 parts of lead and 1 part of bismuth will melt at a 
temperature of 310° Fahr. So this will be the one we 
will select. 

Q. How much H. S. should a locomotive boiler have? 

A. A locomotive boiler should have five times as 
many square feet of H. S. as there are square inches 
area in one of the pistons. 

Q, Where should the safety-plug be placed in a loco- 
motive boiler? 

A. In the center of the crown sheet, or top of the 
fire-box; for that is the highest portion of the boiler 
exposed to the fire. 

Q. Where should it be placed in a return tubular 
boiler ? 

A. In the rear head of the boiler, just above the top 
of the upper row of tubes; for in this class of a boiler 
the top of the upper row of tubes is the highest portion 
of the boiler exposed to the fire : consequently, it would 
be the first part bared to the fire if the water was 
allowed to get low. 

Q. Is there any precaution to be taken in regard to 
the safety-plug when cleaning a boiler? 

A. The safety or fusible plug must be examined when 
cleaning a boiler out, and be carefully scraped on both 
sides to better facilitate its working, in case the water 
were to get low in the boiler. 

Q. How often should safety-plugs be removed in a 
boiler? 



KEY TO STEAM ENGINEERING. 41 

A. It is a good plan to remove them every two or 
three years and have them replaced by new ones, as the 
new ones are a little more reliable than the old ones. 

Q. How do we prepare a boiler for an insurance 
inspection? 

A. The fire should be all cleaned out the evening 
before the inspection is to take place; the clamper should 
be opened to better facilitate the cooling down of the 
boiler. If the boiler is set in brick-work the water 
should not be blown out for at least two hours from the 
time the fire is drawn. If the inspection is to take place 
in the afternoon, it will be time enough to blow the 
water off in the morning; but if in the forenoon, the 
water will have to be k,t out some time during the night. 
Sweep out the tubes and connections to chimney ; also 
sw^eep off* all portions of the boiler shell that can be got 
at, so that the iron can be readily examined. If the 
boiler is of a return tubular or flue style, be sure and 
clean out the dust from combustion chamber. Now 
remove the man-hole and hand-hole plates, and wash or 
scrape out all of the sediment or deposit that may be 
found within the boiler. This will enable the inspector 
to get through in the shortest possible time. 

Q. What is the difference in running a boiler that is 
insured or one that is not? 

A. When we run an insured boiler, the inspectors are 
the ones to be obeyed in all things in connection with the 
boilers ; but if the boilers are not insured, then the engi- 
neer should be the boss. 

Q. If the water was discovered to be out of sight in 
the boiler, or if our water supply through any mishap 
were to be cast off from the boiler, what would be the 
best thing to do? 

A. In case we wanted to suddenly do away with the 
heat under a boiler, shut the dampers and cover the fire 



42 KEY TO STEAM ENGINEERING. 

with ashes, or fine coal, or anything of the kind that can 
be got at. This will cool the furnace clown quicker than 
the old way of drawing the fire. After the fire is covered 
in this way, if it is found necessary it can be drawn. 

Q. Should the engine be shut down in the above case? 

A. If the engine is running, do not stop it ; or if it is 
standing at the time, do not start it. This same rule 
refers to all steam and water valves in connection with 
the boiler. 

Q. Is the loss very much from radiation of the 
exposed parts of boilers and pipes? 

A. Yes ; the loss is a great deal more than most engi- 
neers seem to be aware of. 

Q. What is one of the best coverings for pipes and 
boilers to prevent loss by radiation? 

A. Mineral wool is one of the best as well as the 
neatest covering made, though fossil meal and asbestos 
are often used as coverings to prevent loss by radiation. 

Q. What are the best suggestions that can be given a 
new beginner about firing? 

A. Fire evenly and regularly, a little at a time. Moder- 
ately thick fires are the most economical, but thin firing 
must be the order when the draught is poor. Take care to 
keep the grate evenly covered, and allow no air-holes in 
the fire. Do not " clean" fires oftener than is necessary. 

Q. Why should the heating surface of a boiler be kept 
as clean as possible? 

A. All heating surfaces of a boiler must be kept as 
free from soot and clnst as possible, for they are such 
good non-conductors of heat that they hinder the water 
in a great measure from heating as soon as it other- 
wise would. 

Q. How are boiler tubes usually made? 

A. Boiler tubes are always lap-welded, and annealed 
at both ends; and when we speak of a tube of a certain 
size, we mean the external diameter. 



KEY TO STEAM ENGINEERING. 43 

Q. How are boilers tested? 

A. For testing new boilers we usually give a cold 
water pressure of double the pressure of which we 
intend to run of steam ; but after a boiler has been used 
Ave do not usually give a cold water test of more than 
one-half more than the steam pressure Ave wish to run. 

Q. Of what does the hammer test consist? 

A. The hammer test consists of a person going all 
over the surface of the boiler with a light hammer, 
striking light, even blows, so that if there is a thin place 
or a blister the operator will be able to detect it at once. 

Q. What is a blister on a boiler? 

A. A blister is a puffing out from the body of a boiler 
sheet Avhere the layers of iron are not thoroughly 
Avelded in the process of manufacture. 

Q. What is a bagging or a pocket on a boiler? 

A. Bagging, bulging, or a pocket, are the A^arious 
names given to a SAvelling on the fire-sheets of a boiler, 
generally found near the bridge Avail on return tubular 
or flue boilers. It is different from the blister, as it 
includes the Avhole thickness of a sheet. 

Q. How is the quickest Avay to remove a apor from a 
boiler after it has been blown off ? 

A. The quickest Avay to remove it is to open man-hole 
on top of boiler, then take out hand-hole plate in the 
front connection, shut furnace and ash-pit doors and 
open the damper ; the draught of the chimney will draw 
it all out of the boiler. This rule, of course, refers to 
return tubular or flue boilers. 

Q. Should the Avater be carried at a uniform height 
in a boiler? 

A. Yes ; the water should be carried at a uniform 
height in a boiler to aA^oid fluctuations in temperature 
and A^ariations both in generation and pressure of steam. 

Q. Is there any particular height that Avater should 
be carried in a boiler? 



44 KEY TO STEAM ENGINEERING. 

A. In an average-sized boiler of the return tubular 
or fine pattern, there should never be less than three 
inches of water above the top of the upper row of tubes. 

Q. Suppose the engine stops suddenly from breakage, 
what mnst Ave do with the boiler? 

A. Shut the throttle-valve, open the furnace doors, 
and close the dampers ; bank the fires : and if this is not 
sufficient, pump up and blow off till the boiler is cool 
enough. 

Q. What about cold and hot feed water for boilers? 

A. Great advantage is gained by heating the feed 
water before it enters the boiler, as the chilling of the 
boiler plates is much reduced ; and, further, the waste 
of heat, which means coal, is much reduced. Cold feed 
water, on entering a boiler, settles directly to the bottom, 
contracting the plates, causing deterioration of the metal, 
and often producing rupture of a serious nature. It is 
found that a continuous feed adds to the longevity of a 
boiler and facilitates the maintenance of steam at an 
even pressure. 

Q. How can we tell whether water has been suffered 
to get too low in a boiler? 

A. On examination of the inside of the boiler shell, a 
red coloration will show to about the point the water has 
fallen ; and if there is any scale on the interior of the 
plates, it will be cracked off, so as to leave the iron per- 
fectly clean down to the point to which the water has 
fallen. 

Q. What effect does low water have on the tubes? 

A. If the water has fallen low enough to bare the 
tubes, they will leak at the ends, and if there is any 
scale on them, it will be cracked off down to -the point 
the water has reached. 

Q. How do we proceed if a tube splits? 

A. If dry pine plugs are driven into each end of the 
tube, it can be run till a new tube can be put in. 



KEY TO STEAM ENGINEERING. 45 

Q. Suppose a boiler plate cracks from one of the 
rivet-holes to the edge of the plate, how do you repair it? 

A. A patch will have to be put on. 

Q. Which is the most durable, large or small mud 
drums ? 

A. Small mud drums are the most durable. 
' Q. If you find cracks in the masonry of the boiler 
setting, what do you do, and why? 

JL Point them up at once with cement, mortar or 
clay, to avoid chilling the boiler by the entering air-jets 
and loss of fuel by cooling the gasses. 

Q. What is the proper thickness of fires with soft 
and hard coal? 

A. With hard coal, from 4 to 7 inches ; with soft 
coal, from 5 to 8 inches, depending on the coarseness of 
the fuel and the draught. 

Q. How do you ascertain whether the boiler braces 
are all sound and tight? 

A. By entering the boiler and inspecting them care- 
fully. 

Q. What is the effect of letting ashes accumulate in 
ash-pit? 

A. Insufficient air supply for the fuel on grate and 
liability of burning out the grate bars. 

Q. What is the effect of wetting down ashes and 
clinkers close to the boiler front? 

A. Corrosion of the boiler metal, especially if it is 
an internally fired boiler. 

Q. Is a "shaking grate" preferable to an ordinary 
grate bar? 

A. Yes, by all means, in cases where it can be used. 

Q. Give reasons why. 

A. Because it obviates the necessity of opening the 
furnace doors so frequently, thus keeping the tempera- 
ture of the furnace more uniform, and there is less loss 



46 KEY TO STEAM ENGINEERING. 

of the fine coal dropping through the grate ; it will save 
something in fuel ; it will add to the power of a boiler, 
because the fire can be kept cleaner than with a station- 
ary grate bar ; and, last but not least, it saves a great 
deal in labor. 

Q. Which is best, a spring loaded safety-valve or one 
with weight and lever? 

A. A spring valve is the best, as well as the costliest ; 
though a weight-and-iever is just as safe in the hands of 
a good engineer. 

Q. How would we test the correctness of a safety- 
valve ? 

A. If a weight and lever, by figuring it out as per 
safety-valve rule ; but if a spring valve, by having the 
steam gauge tested and running the pressure up to the 
blowing point on gauge, and seeing if the valve opens. 
The test gauge will prove the weight-and-lever valve 
just as well as the spring valve. 

Q. Why is it advisable to scrape as well as to brush 
or blow out the tubes in a boiler? 

A. A thin, carbonaceous scale is apt to form on the 
inside of the flues or tubes, which, although perhaps not 
thicker than a sheet of paper, requires the expenditure 
of considerable more fuel than if the surface was per- 
fectly clean. 

Q. What will cause external corrosion on a boiler? 

A. Any dampness caused by the boiler, or pipes leak- 
ing, or the roof leaking upon the boiler, will cause corro- 
sion. 

Q. What action does the sulphur in coal have upon a 
boiler? 

A. It forms an acid and corrodes the plates. 

Q. What effect does water impregnated with sulphur 
have upon mud-drums when the feed- water is supplied 
through them? 

A. It corrodes them badly. 



KEY TO STEAM ENGINEERING. 47 

Q. What are the principal impurities found in fresh 
water ? 

A. Carbonate of lime, magnesia, sulphate of lime, 
and. salts of iron. Sometimes nitrates and chlorides are 
found. 

Q. What are the mineral ingredients of sea-water? 

A. Chloride of sodium, potassium and magnesium, 
bromide of magnesium, sulphates of lime and magnesia, 
and carbonate of lime. 

Q. What effect upon the boiling point is caused when 
the water holds foreign substances in solution? 

A. The temperature of the boiling point is raised ; as, 
for instance, fresh water at the sea level boils at a tem- 
perature of 212 c Fahr., while sea-water would boil at 
213.3° Fahr. 

Q. Suppose the pressure of steam in a boiler was 
suddenly lowered, what would be the result? 

A. Steam would be rapidly disengaged from the water 
until the normal relations between the pressure and 
temperature were regained, both pressure and tempera- 
ture being less than before the lowering of the pressure 
took place. 

Q. What is " foaming," and what causes it in a boiler? 

A. Foaming is violent ebullition in a boiler whereby 
water in small particles is thrown among the steam 
particles, mixing with them. It is caused by too little 
steam room ; not sufficient surface at the water-level to 
allow the steam to disengage itself from the water 
quietly ; crowding the tubes too closely in the boiler ; 
from want of good circulation ; from urging a boiler 
beyond its capacity; from oil, grease, or soda in the 
water; and other causes, such as changing from salt 
water to fresh, or the reverse. 

Q. How can foaming be prevented or checked? 

A. By feeding strongly and blowing out, by throttling 



48 KEY TO STEAM ENGINEERING. 

the engine a little, or by putting on a heavy fire to deaden 
clown the heat. But in any case the boiler should be 
emptied and cleaned as soon as possible. 

Q. What danger arises, from it? 

A. If the steam carries much water over the steam- 
pipe into the engine, there is clanger of knocking out a 
cylinder head ; or where steam is used to any extent for 
heating purposes, the Water may be carried to such an 
extent out through the steam-pipes as to bring the water 
dangerously low in the boiler. And even a small amount 
of water carried over into the cylinder of the engine 
does a good deal of harm, for there will be small parti- 
cles of grit in the water that will be carried over, and of 
course they will scratch the inside of the engine more or 
less. 

Q. How are the joints of hand-hole and man-hole 
plates made? 

A. With gaskets, usually of rubber, but sometimes of 
hemp. 

Q. How clo you prevent sticking of the gaskets? 

A. By coating the gaskets on both sides with black 
lead (plumbago) and oil, or gum. 

Q. What is the usual life of a land boiler? 

A. From eighteen to twenty years. 

Q. Of what is putty for joints made? 

A. Generally of white lead, ground in oil, mixed with 
reel lead to make the mass stiff enough to handle easily. 

Q. Why clo we cover the top of a boiler, pipes, etc.? 

A. To prevent cooling of the metal, which would 
cause condensation of the steam and a consequent waste 
of fuel. 

Q. Is a forced draught preferable to * a natural 
draught, or one caused by the chimney alone? 

A. Generally we consider a forced draught the best, 
because it can be kept the same all the time ; whereas, if 



KEY TO STEAM ENGINEERING. 49 

we depend on a natural draught, it will vary with the 
weather. 

Q. What is a " reinforce " patch on a boiler? 

A. It is a hard patch, circular in form, put on the 
outside of a boiler with counter-sunk rivets to give suffi- 
cient thickness to the boiler to allow a pipe to be screwed 
in. This is the way the lower blow-off pipe is always 
attached to the lower part of a boiler. 

Q. What effect does large area of surface at the water 
line of a boiler have on the steam? 

A. It gives dry steam and tends to prevent foaming. 

Q. What effect does contracted steam room have on 
steam in a boiler? 

A. It gives damp steam and tends to induce foaming. 

Q. If a boiler is given to foaming, how can you pre- 
vent water from being carried over into the cylinder of 
the engine? 

A. By carrying the water at a lower level, if possible. 

Q. Should the safety-valve be fitted to the same out- 
let as the steam pipe? 

A. No ; it should be fitted with an independent 
connection. 

Q. What will be the area of the chimney for a boiler? 

A. From i to -^ of the area of the grate surface. 

Q. How thick should the iron be in a flue of from 6 
to 7 inches diameter? 

A. Not less than .18 (y^) of an inch for high 
pressure. 

Q. How thick should the iron be in a flue from 8 to 9 
inches diameter? 

A. Not less than .2 (- x %) of an inch for high pressure 
or marine boilers. 

Q. How thick should the iron be in a flue from 10 to 
11 inches diameter? 

A. Not less than .22 (1%) of an inch for high pres- 
sure or marine boilers. 



50 KEY TO STEAM ENGINEERING. 

Q. How thick should the iron be in a flue from 12 to 
13 inches diameter? 

A. Not less than .23 (- L - 3 -) of an inch for high 
pressure. 

Q. Hoav thick should the iron be in a flue from 14 to 

15 inches diameter? 

A. Not less than .25 (-f- \) of an inch for high 
pressure. 

Q. How thick should the iron be in a flue from 15 to 

16 inches diameter? 

A. Not less than .27 (-^7) of an inch for high 
pressure. 

Q. How much pressure would these flues stand with 
safety ? 

A. If in good condition, from 140 lbs. to 190 lbs. per 
square inch; the smaller one will stand the most. 

Q. How do we determine the pressure per square inch 
allowable on lap-welded flues of not over 18 feet in 
length and from 7 to 16 inches in diameter? 

A. Multiply the thickness of material in hundredths 
of an inch by the constant whole number 44, and divide 
the product by the radius of the diameter of the flue in 
inches ; the quotient will be the pressure allowed. 

Q. If we have a lap-welded flue of 14 inches diameter 
and .25 (y^-) of an inch thick, what pressure would be 
allowed on it? 

A. Proceed thus : 

.25 of an inch thick. 
44 constant whole number. 

100 
100 

Kadius = 7)1100 

157 lbs. pressure to the .sq. in. allowed. 

Always figure this way : consider the .25 just as if it was 

a whole number. 



KEY TO STEAM ENGINEERING. 51 

Q. How high does the Government inspector run the 
cold water pressure above the steam pressure that is 
intended to be run on a boiler? 

A. The hydrostatic pressure is run up to one and one- 
half times the steam pressure to be run. Thus, if 100 
lbs. of steam is to be run, the cold water pressure will 
be run up to 150 lbs. 

Q. What is the greatest strain the Government allows 
to be put on braces, or stays, in her boilers? 

A. Not more than six thousand (6,000) lbs. per square 
inch of cross sectional area ; and they shall not be placed 
at a greater distance than 8.5 (8£) inches from center 
to center. 

Q. How do we figure the bursting strength of boilers? 

A. For a cylindrical boiler, made of either iron or 
steel plates, we multiply the tensile strength of the 
material in pounds by twice the thickness of the iron or 
steel in inches or parts of an inch, and divide the prod- 
uct by the diameter of the boiler in inches. 

Q. Should all boilers be fitted with surface blow-offs? 

A. Yes ; and they are to be used when water is under 
violent ebullition. 

Q. How do we know if a boiler is worked up to its 
full capacity? 

A. If the boiler is running under a natural draught 
it is capable of consuming 12 lbs. of coal per each square 
foot of grate surface per hour. 



52 KEY TO STEAM ENGINEERING. 



SECTION VI. 



ENGINES. 

Q. Wliat is the steam engine? 

A. It is the motor through which steam transmits 
its power to machinery. 

Q. How many classes of engines are there? 

A. Two : throttling, or slide valve, and automatic cut- 
off engines. 

Q. What is the principal difference in the two kinds? 

A. The slide valve costs less. A man of less experience 
can run one, and the repairs, cost of packing, etc., will 
be less than the automatic. The automatic engine will 
pay for itself in from two to four years in the fuel it will 
save over a slide valve engine performing the same work. 

Q. What is the rule for getting the horse-power (H. 
P.) of an engine? 

A. Take the area of the piston in square inches and 
multiply it by the mean pressure per square inch piston, 
then multiply this product by the speed of the piston in 
feet per minute; now divide this last product by 33,000 
and you will have the horse-power of your engine. 

Q. How do we get the area of a piston in square 
inches ? 

A. Multiply the diameter of the piston in inches by 
itself, then multiply the product by .7854 (rWoV) '■> tnis 
will give the area in square inches. 

Q. How do we get the mean pressure per square inch 
on the piston? 



KEY TO STEAM ENGINEERING. 53 

A. With an instrument called the "indicator;" but 
in a slide-valve engine running with a governor, the mean 
pressure will be about one-half of the lowest boiler pres- 
sure that will give the engine full speed. 

Q. How do we get the speed of the piston in feet per 
minute? 

A. Multiply the length of the stroke by two (because 
there are two strokes to each revolution), then multiply 
the product by the number of revolutions per minute the 
engine is making : this will be the speed of engine in feet 
per minute if the stroke was taken in feet ; but if taken in 
inches the last product will have to be divided by 12 (be- 
cause there are 12 inches per foot). 

Q. What difference w T ill there be in getting the H. F. 
of a condensing engine from a common high-pressure 
engine? 

A. In the low-pressure or condensing engine there is 
a gauge to register the amount of vacuum. Take one- 
half of what this gauge registers and acid it to the mean 
pressure if figuring by the slide-valve rule given above. 
If figuring with the indicator, the area of the card is fig- 
ured the same as a high-pressure card. 

Q. Get the H. P. of the following engine (slide-valve) : 
Diameter of piston, 12 inches ; length of stroke, 16 inches ; 
revolutions per minute, 110. The lowest boiler pressure 
that will give the engine full speed is 60 lbs. 

A. Proceed thus : 

16 inches stroke. 
2 strokes per rev. 

32 inches per rev. 
140 revs, per min. 

1280 
32 

12)4480 speed of piston in inches per min. 

373.3 " " feet " " 



54 KEY TO STEAM ENGINEER ING. 



12 in., diam. of the piston. 
12 " " 

24 
12 

144 circular inches, area of piston. 
.7854 times circular inches = sq. in. 

576 
720 
1152 

1008 



Ft. lbs. ) 



113.0976 sq. inches, area of the piston. 
30 lbs., mean pressure on piston. 

3392.928 lbs., total pressure on piston. 
373.3 speed of piston in feet per min. 

10178784 
10178784 
23750496 
10178784 



per H.P. \ 33000)1266580.0224(38.3 -4- H.P. is what this engine i? capa- 
99000 ble of generating. 



276580 
264000 



125800 
99000 

Q. Give good proportions of an 80-H. P. engine of the 
slide-valve pattern. 

A. Diameter of the piston, 15 inches. 

Length of the stroke, 20 inches. 

Sq. in. area of the piston, 177-f-. 

Revolutions per minute, 172. 

Speed of the piston, 573+ feet per minute. 

Mean pressure on piston, 26 lbs. 

The cnt-off of steam takes place at about f that of 
the stroke. 

Length of the crank, 10 inches. 

Length of the connecting rod, 50 inches. * 

Diameter of the piston rod. 2 inches. 

Diameter of the valve rod, 1| inches. 

Diameter of the steam pipe, 3 J inches. 

Diameter of the exhaust pipe, -U inches. 



KEY TO STEAM ENGINEERING. 55 

Area of steam ports, each, 10^ square inches. 
Area of exhaust port, 24^- square inches. 
Area of steam pipe, 11^ square inches. 
Area of exhaust pipe, 14^ square inches. 

Q. How is the speed of an engine governed? 

A. The speed of an engine is regulated by the governor. 
In the throttling engine it throttles the steam in the sup- 
ply pipe, but in the automatic engine it regulates the ad- 
mission valves in the quantity of steam they admit to the 
cylinder. 

Q. What is meant by terminal pressure? 

A. By terminal pressure we mean the pressure of 
steam in the cylinder just as it is released. 

Q. What is meant by mean pressure? 

A. The average pressure per square inch throughout 
the stroke. 

Q. What is meant by initial pressure? 

A. It is the pressure of steam as it enters the cyl- 
inder. 

Q. What is meant by gauge pressure? 

A. It is pressure per square inch above the atmos- 
pheric pressure. 

Q How could the terminal pressure of steam be 
found? 

A. Multiply the initial pressure by the number of 
inches the piston has travelled when the cut-off of steam 
takes place, and divide the product by that portion of the 
stroke in inches at which the release or exhaust valve 
opens. The quotient will be the terminal pressure. 

Q What three things give us power in an engine? 

^4. Size, pressure and speed. 

Q. Upon what does the steam act to give us power in 
the steam engine? 

A. The steam is admitted to the cylinder between the 
piston and cylinder head, the head being bolted on to the 



56 KEY TO STEAM ENGINEERING. 

cylinder firmly, of course. The piston is the part that is 
driven with the force of the steam to the opposite end of 
the cylinder. There the operation is repeated, and the 
piston is driven back to its former place. 

Q. AVhat is the length of the crank on an engine? 

A. The length of the crank is just one-half of the 
length of the stroke of the engine. 

Q. How many strokes does an engine or pump make 
for each revolution ? 

A. Two strokes per revolution. 

Q. What should be the diameter of the steam supply 
pipe for the engine? 

A. About one-fourth the diameter of the piston. 

Q. How much larger should the exhaust pipe be than 
the steam supply pipe for the engine? 

A. The exhaust pipe for letting the steam out of the 
engine after it has done its work should be one-fifth 
larger than the steam pipe. 

Q. In a slide-valve engine what will be the diameter 
of the valve rod? 

A. About one-twelfth of the diameter of the piston. 

Q. What will be the diameter of the piston rod? 

A. In a slide-valve engine, usually about one-eighth of 
the piston diameter ; but for high pressure, such as we 
usually get in automatic engines, we have a special rule 
which will appear later. 

Q. What are steam ports in a steam engine? 

A. Steam ports are the passages through which the 
steam is admitted from the steam chest to the cylinder. 

Q. How do you find the area or size that these steam 
ports should be to admit steam enough to the cylinder? 

A. Take the area of the piston in square inches and 
divide it by 19 ; this will give you the area of each steam 
port in square inches if the speed of the piston is not to 
exceed 500 feet per minute. If the speed is greater than 



KEY TO STEAM ENGINEERING. Oi 

500 feet per minute, then we would take the area of the 
piston in square inches and multiply it by the speed of 
the piston in feet per minute, and divide the product by 
10,000; this will give the area of each steam port in 
square inches. 

Q. What is meant by the exhaust port? 

A. It is the passage through which the steam comes 
back from the cylinder after doing its work there. 

Q. How do we get the area of the exhaust port? 

A. For a slide-valve engine with one central exhaust 
port they usually have the area of it about one-eighth of 
the area of the piston, or one-fifth larger than the area 
of both steam ports combined. 

Q. What are the five principal places to oil on any 
engine? 

A. The inside of the steam chest and the cylinder, the 
two main bearings on the crank shaft, the crank pin, and 
the eccentric. 

Q. What four things are most apt to make our engine 
heat up her bearings? 

A. Our main belt being very taut, keying up or tight- 
ening up too much, dust or dirt of any kind getting into 
the bearings, or if our engine is in a very hot room. 

Q. Which is the cheaper, a leather or a rubber belt for 
a main belt from our engine? 

A. In most cases a rubber belt will be the cheaper. 

Q. How many kinds of oil do we use on an engine? 

A. Two ; cylinder oil, which will stand from 400° to 
600° of heat, for the inside of steam chest and cylinder, 
and common machinery oil for all external parts. 

Q. What is a good length for a connecting rod (the 
rod which connects the cross-head to the crank) for an 
engine? 

A. About five times the length of the crank, center to 
center. 



58 KEY TO STEAM ENGINEERING. 

Q. When is the best time to key up or tighten up the 
bearings on an engine? 

A. When the engine is warm, as it will be after run- 
ning a few hours, for then the pins, journals, etc., have 
had sufficient chance to expand all that they will with the 
maximum running temperature. 

Q. How is the best way to oil an engine? 

A. Put on a little at a time, and often. 

Q. What are some of the principal clangers an engine 
is subjected to? 

A. Water getting too high in the boilers and coming 
over into the steam pipe, and from there into the cylinder, 
is liable to knock out a cylinder head ; bearings getting 
heated ; nuts or keys working loose. 

Q. What are some of the most important things for 
an engineer to look after? 

A. To see that the steam does not get too high ; to see 
that the water does not get too low ; to see that the water 
does not get too high ; to see that the bearings do not get 
hot, nor anything work loose about the engine; to see 
that the steam does not get too low ; and, last of all, keep 
everything clean in and about the engine and boiler room. 
These are the engineer's duties in their order of impor- 
tance. 

Q. What is another difference between the automatic 
and the slide-valve engines? 

A. In the slide-valve engine one valve performs the 
four separate operations of letting steam alternately into 
both ends of the cylinder and out of it, while in the auto- 
matic engine there are four separate valves to perform 
the same work. 

Q. Do we know where the steam is cut off in an auto- 
matic engine? 

A. We do not as a general thing; for if the work 
varies, the cut-off will vary. 



KEY TO STEAM ENGINEERING. 59 

Q. What is the difference in the amount of water con- 
sumed with slide-valve and automatic engines? 

A. Automatic engines use from 20 to 30 lbs. of water 
per H. P. per hour, while slide-valve engines use from 40 
to 60 lbs. of water per H. P. per hour. 

Q. What is the difference in the consumption of coal 
in the two engines? 

A. The Corliss valve gear was the first automatic 
engine made, and is considered about the average today ; 
it will consume about 2)4 lbs. of coal per H. P. per hour. 
The average slide-valve engine will consume from 3)4 to 
4 lbs. of coal per H. P. per hour. 

Q. What is the extreme variation of coal consumption 
of the different engines used today? 

A. From 2 to 5 lbs. of coal per H. P. per hour. 

Q. How do we find the proper length of steam ports 
on the cylinder side of a slide-valve engine? 

A. Divide the diameter of the cylinder by 1.2 (lyV) 5 
the quotient will be the length required. 

Q. If we have the area of a piston given, which is the 
quickest way to find the area of the steam supply and the 
exhaust pipes? 

A. Divide the area of the piston by 16; the quotient 
will be the area of the steam supply pipe. And if we 
divide the area of the piston by 13, the quotient will be 
the area the exhaust pipe ought to be. 

Q. How do we find the area of a piston rod where 
high-pressure steam is to be run, as in the automatic 
engine? 

A. The proper way to find the area of a piston rod in 
an automatic engine is to multiply the area of the piston 
in square inches by the highest boiler pressure to be run, 
and divide the product by 4.480 ; nine-tenths of the quo- 
tient will be the area in square inches that the piston rod 
should be if made of steel. 



60 KEY TO STEAM ENGINEERING. 

Q. What is a good proportion between diameter of 
cylinder and the length of stroke of an engine? 

A. For most work the proportion of the diameter of 
the cylinder to the length of stroke is as 3 to 4. The 
well-known Corliss has a proportion of 1 to 2 ; but some 
builders (as the Armington & Sims Mfrs.) construct their 
engines k ' square, " that is, the diameter of cylinder is the 
same as the length of stroke. 

Q. How do we set a slide valve? 

A. To set a slide valve is simply to lengthen or shorten 
the distance between the eccentric and valve, or, as some 
authorities say, to equalize the vibrations of the valve. 
It does not make any difference whether the eccentric is 
set or not. In setting a valve, all we have to do is to 
see that it is made fast to the shaft and that all the con- 
nections are tight enough for running order. 

Q. How do we set an eccentric? 

A. Place the engine on one of the dead centers. Now 
turn the eccentric in the direction we wish the engine 
to run until the part corresponding to the end the piston 
is at commences to open ; make the eccentric fast to the 
shaft; then turn the engine round to the other dead 
center and see if the valve has the same amount of lead 
or opening there. For an engine of ordinary speed 
(from 300 to 500 feet per minute) , give the valve about 
■gL of an inch lead. If the engine is run faster, give 
more lead. 

Q. In a new engine, which has to be set first, the 
valve or eccentric? 

A. The valve must always be set first in the slide- 
valve engine, for the eccentric could not be set until the 
valve had been. 

Q. What is meant by lead and lap of a valve? 

A. The distance that the steam ports are open when 
the engine is on the dead center is called the lead, and 



KEY TO STEAM ENGINEERING. 61 

the distance the valve reaches beyond the steam ports at 
either end, when the eccentric is at one-half stroke, is 
called the lap of the valve. 

Q. About how many living horses is a steam H. P. 
equal to? 

A. A steam H. P. is equal to about three average 
horses' power. An average horse is equal to about 
seven average men in power. 

Q. Is there any other standard for measuring the 
power of engines? 

A. There are only two systems of measuring the 
power of engines used in Europe or America, viz. : the 
English standard, fixed by James Watt, which is 33,000 
lbs. raised one foot high in one minute's time, equals one 
H. P. ; and the French, which is called the force du cheval ; 
this is based on the metric system, and is 4,500 kilograms 
one meter high in one minute's time. This will be about 
-r±z less than our standard. 



62 KEY TO STEAM ENGINEERING. 



SECTION VII. 



BELTS, SHAFTING, SPEED. 

Q. How does the power of belts increase? 

A. The power that a belt can transmit varies directly 
as its width and speed (if all other conditions remain 
the same) with a limit of 5,000 to 6,000 feet per minute ; 
that is, this has been found to be about the greatest 
speed advisable to run belts. 

Q. What other conditions are there to be considered? 

A. There are two other things to be considered : 
first, the thickness, and next, the tautness of the belts. 

Q. What is it gives us power in belts? 

A. Friction is what enables us to transmit power 
with belts. 

Q. What three things give us the friction in belts? 

A. Surface the belt covers, speed that it travels and 
the pressure that is brought to bear upon it. 

Q. How fast will a one-inch single leather, or a three- 
ply rubber, belt have to travel to be able to transmit one 
H. P.? 

A. A one-inch single leather or a three-ply rubber 
(which are of about the same thickness and weight) 
would have to travel 800 feet per minute to transmit 
one H. P., or 1,600 feet per minute to transmit two 
H. P., and 2,400 feet per minute to transmit three 
H. P., and so on; this is running them as taut as they 
should be run. 

Q. How fast will a two-inch belt have to run to be 
able to transmit one II. P.? 

A. A two-inch single leather or a three-ply rubber 
belt will have to run 400 feet per minute to transmit one 
H. P.; 800 feet per minute to transmit two II. P.: 1,200 
feet per minute to transmit three II. P., and so on. 



KEY TO STEAM ENGINEERING. 63 

Q. How many different thicknesses of belts are there? 

A. Leather belts come in two thicknesses, single and 
double ; rubber belts come in four thicknesses, three-ply, 
four-ply, five-ply and six-ply. 

Q. How does the strength of shafts increase? 

A. The strength of shafts, for either a binding or a 
twisting strain, varies as their speed and the cube of 
their diameters ; for a two-inch shaft will do eight times 
as much work as a one-inch shaft running the same speed. 

Q. How fast will a one-inch shaft have to run to 
transmit one H. P.? 

A. A one-inch shaft running 100 revolutions per 
minute will transmit one H. P.; 200 revolutions per 
minute, two H. P. ; 300 revolutions per minute, three 
H. P., and so on. 

Q. How much strain would a one-inch shaft twelve 
feet long stand at the end of a crank one foot long? 

A. It would safely stand 50 pounds. 

Q. How fast will a two-inch shaft have to run to 
transmit one H. P.? 

A. A two-inch shaft running 124 revolutions per 
minute will transmit one H. P. ; 25 revolutions per 
minute, two H. P. ; 50 revolutions per minute, four H. P., 
and so on. 

Q. How many H. P. will a three-inch shaft transmit, 
running 100 revolutions per minute? 

A. Twenty-seven H. P., and if it run 200 revolutions 
per minute it would transmit 54 H. P., and so on. 

Q. How do we find the maximum H. P. of a shaft, 
within good working limits? 

A. Multiply the cube of the diameter of the shaft in 
inches by the speed in turns per minute, and divide by 
205 if a cast-iron shaft, or by 110 if wrought iron, or by 
82 if a steel shaft. The quotient is the H. P. of shaft. 

Q. How do we And the diameter of a shaft capable of 
transmitting a given H. P. within good working limits? 



64 KEY TO STEAM ENGINEERING. 

A. Multiply the H. P. by 205 if a cast-iron shaft, or 
by 110 if wrought iron, or by 82 if a steel shaft, and 
divide by the speed in turns per minute. The cube root 
of the quotient is the diameter in inches. 

Q. How do we find the speed required to run a shaft, 
for transmitting a given H. P. within good working 
limits? 

A. Multiply the H. P. by 205 if a cast-iron shaft, or 
by 110 if a wrought iron shaft, or by 82 if a steel shaft, 
and divide the product by the cube of the diameter of 
the shaft in inches. The quotient is the speed in turns 
per minute. 

Q. How do we find the size of a driving pulley to give 
another shaft a given speed, where speed of driving and 
driven shafts are known as well as the size of driven 
pulley ? 

A. Multiply the diameter of the driven by the number 
of revolutions per minute it is running, and divide the 
product by the revolutions of the driving shaft. The 
quotient will be the diameter of the driving pulley. 

Q. How do we find the size of a driven pulley? 

A. Multiply the diameter of the driving pulley by its 
number of revolutions per minute, and divide the prod- 
uct by the number of revolutions per minute the driven 
shaft is to run. The quotient will be the diameter of 
the driven pulley. 

Q. How do we find the speed of a driven shaft, where 
speed of driving shaft is known, as well as size of both 
driving and driven pulley? 

.1. Multiply the diameter of the driving pulley by the 
number of revolutions it runs per minute, and divide the 
product by the diameter of the driven pulley. "The quo- 
tient will be the number of revolutions the driven shaft 
makes per minute. 

Q How do we find the relative amount of centrifugal 
force of different pulleys? 



KEY TO STEAM ENGINEERING. 65 

A. If there be two wheels of the same weight, and 
making the same number of revolutions per minute, but 
the diameter of one be double that of the other, the lar- 
ger will have double the amount of centrifugal force ; 
or if the velocity of a wheel be doubled it will have four 
times the amount of force. 

Q. How many different rules have we for finding the 
area of circles? 

A. Five, as follows : Multiply the circumference by 
J- of the diameter ; multiply the square of diameter by 
.785-4 (tW-qV) 5 multiply the circumference by .07958 
(rcpftHb") ; multiply \ of the circumference by ^ of the 
diameter ; and multiply square of the radius (^ diam.) by 
3.U16 (SftWW- 

Q. What do we know about circles? 

A. Diameter of a circle multiplied by 3.1416, the prod- 
uct equals the circumference ; circumference divided by 
3.1416, the quotient equals the diameter; diameter multi- 
plied by .8862 (yi^o%)' tne product equals side of a square 
of equal area ; and a side of a square divided by .8862, the 
quotient equals diameter of a circle of equal area. 

Q. What do we know about a cubic foot? 

A. A cubic foot equals 1,728 cubic inches; 2,200.15 
cylindrical inches ; 3,300.23 spherical inches ; 6,600.45 con- 
ical inches; 62.32 lbs. of fresh water at a mean temper- 
ature; 7.48 United States standard gallons; 452 lbs. cast 
iron ; 485 lbs. wrought iron, and 489 lbs. of steel. 

Q. How many different thicknesses of steam pipe are 
there? 

A. Three: the common, which is the lightest; the 
extra, and the double-extra, which is the thickest; exter- 
nal diameters are all same size. 

Q. How are the internal diameters? 

A. The size of steam pipe goes by the internal diam- 
eter, as for instance, a one-inch extra steam pipe is just 



<)6 KEY TO STEAM ENGINEERING. 

one inch inside diameter ; the one-inch common steam 
pipe is a little more than an inch inside diameter, and 
one-inch double-extra is not quite one inch inside 
diameter. 

Q. How long does the steam pipe come? 

A. The regular length is 16 feet. 

Q. What is the smallest and largest wrought iron 
steam pipe made? 

A. The smallest steam pipe made is I of an inch and 
the largest is 24 inches diameter, but it has been pro- 
posed to make it of even 42 inches diameter. 

Q. How many different w^ays have we of welding pipe 
together ? 

A. Two, the " lap weld" and the " but weld." Boiler 
tubes are always "lap welded," and unlike the steam 
pipes they are rated by their external diameter. 

Q. What is a good receipt for a solder? 

A. Coarse plumbers' solder contains lead, two parts ; 
tin, one part; common solder contains equal parts of 
the two metals ; fine solder is composed of two parts of 
tin and one part of lead. 

Q. What is a good thing for cleaning brass-work on 
engines and boilers? 

A. There is nothing better than oxalic acid and salt 
water, in the proportion of \ an ounce of acid to a pint 
of salt water. 

Q. What of the common metals expands the most? 

A. Zinc expands the most, copper the next and brass, 
of course, being composed principally of copper, expands 
nearly as much as the copper. 

Q. How is a good way of measuring belting in the 
roll? 

A. Take the sum of the inside and outside diameters 
in inches and multiply it by the number of turns made 
by the belt (in the roll), then multiply the product by 
.1309 (iVoo 9 u) > this wiU & ive the tength of the belt in feet. 



COMBUSTION CHEMICALLY CONSIDERED. 



PK FST I I. 



SECTION I. 



COMBUSTION OF COAL 

CHEMICALLY CONSIDERED. 

In any attempt to ascertain how to develop the largest 
percentage of real paying duty from a given amount of 
fuel — the most heat and power — our first inquiry 
should be as to the nature of the fuel and the elements 
of combustion that enter into it — considered from a 
chemical standpoint. 

From scientific analyses by Professor Liebeg and 
others, it is shown that in the various kinds of soft or 
bituminous coal there is about 80 per cent of carbon, 
5 per cent of hydrogen, 10 per cent of azote and oxygen 
and 5 per cent of ash ; these proportions varying some- 
what in the different kinds. The principal constituents 
of all coal, however, are carbon and hydrogen, which are 
united and solid in its natural state. In all bituminous 
coal hydrogen is the main element from which gas is 
evolved, and by the combustion of which flame is 
produced. 

Their main constituents, carbon and hydrogen, united 
in the solid coal are essentially different in character and 
in their modes of entering into combustion, and to the 
ignorance or neglect of this primary distinction, much 
of the waste and uncertainty attending the use of coal 
on a large scale is due. The theory of combustion is 



68 COMBUSTION CHEMICALLY CONSIDERED. 

well understood by scientific men, yet practically the art 
of burning coal economically remains at a low ebb, and 
the science of converting the natural elements of coal 
into heat and power is but little understood. While it is 
well knoAvn that the constituents of coal — carbon and 
hydrogen — require certain quantities of atmospheric 
air to effect their combustion, yet practically the means 
necessary to ascertain what quantity is supplied is often 
neglected and the matter is generally treated as though 
the right proportion was unimportant. While theoreti- 
cally the relative constituents of which atmospheric air 
is composed are generally well known, yet practically the 
nature of these constituents or their effects in combus- 
tion is often totally ignored. It is known scientifically 
that the inflammable gases are combustible and converti- 
ble into heat, only in proportion to the right mixture and 
union effected between them and the oxygen of the air ; 
yet in practice we are not apt to trouble ourselves as to 
whether such mixture is effected or not, These and 
similar illustrations indicate a lack of practical knowl- 
edge of how best to utilize the natural elements of coal 
so as to produce heat and power economically. 

The bituminous portion of coal is convertible to heat 
in the gaseous state alone, while the carbonaceous por- 
tion on the contrary is combustible only in the solid 
state, and neither can be consumed while they remain 
united ; hence to effect combustion their separation must 
be effected and a new union formed with other elements, 
viz., atmospheric air or oxygen. In combustion, there 
must be a combustible and a supporter (oxygen) of com- 
bustion, which means, chemical union. 

Until all the bituminous constituents are evolved from 
coal its solid or carbonaceous part remains black at a 
comparatively low temperature, and inoperative as a 
heating body, and must wait for the heat essential to its 
combustion in its own peculiar way. And if the bitumi- 



COMBUSTION CHEMICALLY CONSIDERED. 69 

nous part be not consumed or utilized, it would be 
better were it not in the coal, in which case such heat 
would be saved and available for duty. To this fact 
may be attributed the alleged greater heating properties 
of anthracite coal or coke over bituminous coal. 

Having noticed the leading properties of coal in its 
natural state and the elementary divisions, bituminous 
and carbonaceous, the next important consideration is 
its union with the atmospheric air ; and it will be found 
that the practical economy in the use of coal is intimately 
connected with the combustion of the gases evolved 
from the coal, which cannot be effected without a suitable 
mixture with the air, the principal supporter of com- 
bustion. 

Eresh coal supplied to the glowing coals in the furnace 
does not immediately or instantly increase the general 
temperature, but becomes an absorbent of it and the 
source of the volatization of the bituminous portion of 
the. coal (of the generation of gases) ; and volatization is 
the most cooling process of nature, by reason of the 
quantity of heat directly converted from the " sensible" 
to the " latent " state. 

On the application of heat to bituminous coal, the first 
result is its absorption by the coal and the disengage- 
ment or liberation of the gases, from which flame is 
exclusively derived. The constituents of this gas are 
hydrogen and carbon; and the union is called carburetted 
hydrogen and bi-carbnretted hydrogen, commonly called 
defiant gas. This carburetted hydrogen though not a 
combustible — taken by itself — becomes a combustible 
when united with oxygen (and for this reason oxygen is 
called a "supporter"), neither of ichich, however, taken 
alone can be consumed. Coal gas, whether generated in 
a retort or furnace, is essentially the same. By itself it 
is not inflammable, can neither produce flame nor permit 



70 COMBUSTION CHEMICALLY CONSIDERED. 

its continuance in other bodies. A lighted taper is 
instantly extinguished, if introduced into a tank of 
hydrogen gas. In short, for all practical purposes com- 
bustion is more a question of air than gas. 

In the common gas-burner we have an illustration of 
our ability to control the gas for light and heat. In the 
furnace, however, we have no control over the gases, 
as to quantity, after throwing on the coal, but can exer- 
cise considerable control over the air, in all essentials to 
perfect combustion. This control of the air is what has 
brought the lamp to such perfection, and may be made 
equally available for the furnace. The difficulty in the 
way is, that it has to be controlled on a much larger 
scale, but as regards quantity and quality, the principle 
is the same. How, when and where this controlling 
influence over the admission of air is to be exercised to 
the best advantage in burning fuel in a furnace, are 
questions demanding the most careful attention of the 
practical engineer, and they must be decided on strict 
chemical principles * 

The first essential in effecting the combustion of gas 
is to ascertain the quantity of oxygen with which it will 
chemically combine ; next, the quantity of air required 
to supply the necessary quantity of oxygen. Now while 
this may be scientifically understood and correctly 
arrived at by an expert chemist in the laboratory, it, 



*In ordinary language, a body is said to burn when its elements 
unite with the oxygen of the air and form new products. One of the 
bodies, as hydrogen, is termed the burning or combustible body, 
and the oxygen is said to be the supporter of combustion ; but this 
language, although convenient for common use, is incorrect as 
a scientific expression, for oxygen may be burned in a vessel of 
hydrogen, as well as hydrogen in a vessel of oxygen; the one and 
the other being equally active in the process, and being related 
to each other in every way alike. — Elements of Chemistry, by 
Robert Kane, M.D. 



COMBUSTION CHKMICAIXY CONSIDERED. (1 

however, is to be expected that, in the management 
of combustion in a furnace, the ordinary engineer 
can at best only approximately apply the exact laws of 
chemistry to the very imperfect conditions found at 
every furnace. It is important, however, that every 
engineer should, at least, understand theoretically the 
analysis of the elements he has to deal with in producing 
combustion, and the proportional part of each element 
entering into the same ; therefore, a brief treatment of 
this subject from a chemical point of view is here pre- 
sented, selected from the writings of the best authorities 
on this subject. 

According to chemical analysis, an atom of hydrogen is 
double the bulk of an atom of carbon vapor ; yet the latter 
is six times the weight of the former. Again, an atom of 
hydrogen is double the bulk of an atom of oxygen ; yet 
the latter is eight times the weight of the former. So of 
the constituents of atmospheric air, nitrogen and oxygen. 
An atom of the former is double the bulk of an atom of 
the latter ; yet in weight, it is as fourteen to eight. It 
is also ascertained that oxygen is but one-fifth of the bulk 
of air. Five volumes of the latter (air) will necessarily 
be required to produce one of the former (oxygen). 
And, as we want two volumes of oxygen for each volume 
of the coal gas, it follows that, to obtain those two vol- 
umes, we must provide ten volumes of air. 

Thus far the subject has been treated mainly with 
reference to the supply of air required for the saturation 
and combination of the gaseous portion of coal. We will 
now consider a corresponding question with reference 
to the carbonaceous part of coal, which rests upon th« 
grate-bars in a solid form, after the gaseous matter has 
been evolved therefrom. 

It is stated by chemists, that carbon is susceptible of 
uniting with oxygen in three proportions, by which three 



72 COMBUSTION CHEMICALLY CONSIDERED. 

distinct bodies are formed, possessing distinct chemical 
properties. Although this peculiarity of the union of 
carbon with oxygen is almost wholly neglected in prac- 
tice, yet it is very essential in correctly estimating the 
quantity of air which should be admitted to the furnace. 

These proportions, in which carbon unites with oxygen, 
form: 1. Carbonic acid ; 2. Carbonic oxide ; and o. Car- 
bonous or oxalic acid. With the first and second, we 
have to deal principally in the furnace. Carbonic acid is 
a compound of one atom of carbon with two atoms of oxy- 
gen ; while carbonic oxide is composed of the same 
quantity of carbon with but half the above quantity of 
oxygen. Here we see that carbonic oxide, though con- 
taining but one-half the quantity of oxygen, is yet of the 
same volume as carbonic acid, which is of considerable 
importance on the question of draught and supply of air. 
Now the combustion of this oxide by its conversion into 
the acid, is as distinct an operation as the combustion 
of the carburetted hydrogen, or any other combustible ; 
yet all this is almost entirely overlooked in practice at the 
furnace. 

Outside of the laboratory, and in actual practice, but 
little is known as regards the formation of this oxide. The 
direct effect of the union of carbon and oxygen is the forma- 
tion of carbonic acid. If, however, we abstract one of its 
portions of oxygen, the remaining proportions would 
then be those of carbonic oxide. It is equally clear that 
if we add a second portion of carbon to carbonic acid, 
we shall arrive at the same result, namely, have carbon 
and oxygen combined in equal proportions, as we have 
in carbonic oxide. By the addition of still another por- 
tion of carbon two volumes of carbonic oxide will be 
formed. Now, if these two volumes of carbonic oxide 
cannot find the oxygen required to complete their saturat- 
ing equivalents, they pass away necessarily but half con- 



COMBUSTION CHEMICALLY CONSIDERED. to 

sumed — a process which is constantly going on in all 
furnaces, where all the air has to pass through a body of 
incandescent carbonaceous matter. 

This frequently leads to a common error in what is 
called the "combustion of smoke"; for if the carbon- 
aceous constituent of coal, while yet at a high temper- 
ature, encounters carbonic acid, this latter, taking up an 
additional portion of carbon, is converted into carbonic 
oxide and again becomes a gaseous and invisible combus- 
tible. The most prevailing operation of the furnace, 
however, by which the largest quantity of carbon is lost 
in shape of carbonic oxide, is thus : The air, on entering 
from the ash-pit, gives out its oxygen to the glowing car- 
bon on the bars, and generates much heat in the formation 
of carbonic acid. This acid, necessarily at a very high 
temperature, passing upwards through the body of incan- 
descent solid matter, takes up an additional portion of 
carbon, and becomes carbonic oxide.* 

Thus by the conversion of one volume of acid into two 
volumes of oxide, heat is actually absorbed, while the 
carbon taken up during such conversion is also lost, and 
we are liable to be deceived by imagining we have 
" burned the smoke." 

The formation of this compound, carbonic oxide, being 
thus attended by circumstances of a curious and involved 
nature, is probably the cause of the prevailing ignorance 
of its properties ; for, while we find everywhere the term 
carbonic acid, as a product of combustion, we hear 



* "Carbonic oxide may be obtained by transmitting carbonic acid 
over red-hot fragments of charcoal contained in an iron or porcelain 
tube. It is easily kindled ; combines with half its volume of oxygen, 
forming carbonic acid, which retains the original volume of car- 
bonic oxide. The combustion is often witnessed in a coke or char- 
coal fire. The carbonic acid produced in a lower part of the fire is 
converted into carbonic oxide as it passes up through the red hot 
embers." — Graham's Elements of Chemistry. 



74 COMBUSTION CHEMICALLY CONSIDERED. 

nothing of carbonic oxide — one of the most waste-induc- 
ing compounds of the furnace, unless provided with its 
equivalent volume of air, by which its combustion will 
be affected.* 

Another important peculiarity of this gas (carbonic 
oxide) is that, by reason of its already possessing one- 
half its equivalent of oxygen, it inflames at a lower 
temperature than the ordinary coal-gas ; the consequence 
of which is, that the latter, on passing into the flues, is 
often cooled clown below the temperature of ignition ; 
while the former is sufficiently heated, even after having 
reached the top of the chimney, and is. there ignited on 
meeting the air. This is the cause of the red flame often 
seen at the top of chimneys, or the funnels of steam- 
ships. 

We may thus conclude for a certainty, that, if the 
carbon, either of the gas or of the solid mass on the 
bars, passes away in union with oxygen in any other 
form or proportion than that of carbonic acid, a propor- 
tionate loss of heating effect is the result. 

According to chemical analysis ten cubic feet of air is 
required to supply two cubic feet of oxygen to effect the 
combustion of one cubic foot of coal-gas ; but if this 
quantity of air does not contain this 20 per cent, it is 



* "Among the stove-doctors of the present day, none are more 
dangerous than those who, on the pretense of economy and con- 
venience recommend to keep a large body of coke burning slowly, 
with a slow circulation of air. An acquaintance with chemical 
science would teach them, that, in the obscure combustion of coke 
or charcoal, much carbonic oxide is generated, and much fuel con- 
sumed, with the production of little heat ; and physical science 
would teach them, that, when the chimney draught is languid, 
the burned air is apt to regurgitate through every seam or crevice, 
with the imminent risk of causing asphyxia, or death, to the in- 
mates of apartments so preposterously heated." — Dr. lire's Paper 
on Ventilating and Heating. (Read before the Royal Society.) 



COMBUSTION CHEMICALLY CONSIDERED. ID 

clear we cannot obtain the requisite amount. Therefore, 
when we speak of mixing a given quantity of oxygen 
with a given quantity of coal-gas, it is because we know 
that the former is required to saturate the latter ; so 
when we speak of mixing a given volume of atmospheric 
air with a given volume of coal-gas, we do so knowing 
that such precise quantity of air will provide the requisite 
quantity of oxygen. If, however, by any means, the air 
employed has either lost any portion of its oxygen, or is 
mixed with any other gas or matter, it no longer bears 
the character of pure atmospheric air, and cannot satisfy 
the condition required as to quantity of oxygen which i^ 
essential. The air in such cases may be said to be dete- 
riorated or vitiated, and therefore the quality of the air 
employed is entitled to consideration. 

Having considered the constituents of coal; the necessary 
conditions to perfect combustion ; the nature of the gases 
evolved from coal ; the proper mixture of the gases with 
oxygen — the promoter of combustion — and the quantity 
and quality of the air employed, let us now inquire how 
far the usual methods of constructing and managing fur- 
naces satisfy those conditions. 

First, it should be noticed, that the conditions required 
vary somewhat in the different kinds of fuel, especially 
in anthracite and bituminous coal; there being in the 
latter larger quantities of hydrogen gas to utilize, with 
which a separate and suitable quantity of air or oxygen 
must be mixed to get the best results in the way of heat 
and power. 

The two distinct operations of supplying air to the gas 
generated in the upper part of the furnace, and to the 
carbon resting on the grate-bars, is not sufficiently con- 
sidered in daily practice. By the usual method, the 
whole supply of air is compelled to pass through the 
ash-pit, and the solid carbon upon the bars ; the 



76 COMBUSTION CHEMICALLY CONSIDERED. 

air which has already been employed in a separate 
and destructive process is tlms brought to the gases, 
insufficient in quantity and quality ; and it is expected 
that the result will be satisfactory and combustion com- 
plete ; then, when it is found that, instead of producing 
carbonic acid and water, we have produced a large 
volume of smoke or unconsumecl combustible matter, we 
set about inventing some process by which this " smoke " 
is to be consumed. 

There are a number of so-called " smoke-consumers." 
It is, however, no part of the writer's purpose to show 
how smoke can be burned, but to show the conditions 
necessary to burn coal without smoke. On the contrary, 
we contend that, when smoke is once produced in a 
furnace, it is as impossible to burn it or to convert 
it into heat as it is to convert the smoke from the flame 
of a candle or lamp into light and heat. In short, with- 
out controlling the air, but poor results are obtained in 
either case. For an illustration, take an Argancl burner, 
poorly or improperly adjusted, as regards the air, and 
we get a smoky, murky light; properly adjusted, as re- 
gards the air, we get a white, clear light and heat. In 
the latter case, would it be correct to say, the "lamp 
burns its smoke," or the " lamp burns without smoke?" 

Knowing the quantity and quality of air to be admitted 
to the furnace, the next important consideration is the 
discovery of the best method of S2ich a mixture of the air 
and gases required for complete combustion. There have 
been many mechanical devices for supplying the gases 
above the coal in the combustion -chamber with fresh air, 
each possessing more or less merit, but in this direction 
there is still room for great improvement; andit will be 
found that any mechanical device, that does not carefully 
take into account the principles of chemistry, will never 
accomplish the desired result. 



COMBUSTION CHEMICALLY CONSIDERED. 77 

In common practice it is taken too much for granted, 
that, if air by any means be introduced to the furnace, 
it will, as a matter of course, mix with the gases liber- 
ated from the coal or other combustibles, whatever be 
the nature or state of such fuel. It is, however, the 
proper distribution of the air, and the bringing together 
bodies of gas and air in a state of preparation, so that 
the requisite mixture of all the elements will be incor- 
porated and utilized, that effects perfect combustion. 

It should be observed, that in effecting these mixtures 
of gases, they will properly combine and become united, 
if sufficient time be allowed ; but in the furnace, as it is 
impossible to force the gas and air to mingle with suffi- 
cient rapidity under ordinary circumstances, our atten- 
tion should be directed towards making such modifica- 
tions of the furnace as will aid nature in those operations 
essential to combustion. 

Prof. Daniels says, " There can be no doubt that the 
affinity of hydrogen for oxygen, under most circum- 
stances, is stronger than that of carbon." He further 
says, "With regard to the different forms of hydro- 
carbon, it is well known, that the whole of carbon is 
never combined with oxygen in process of detonation or 
silent combustion, unless a large excess of oxygen be 
present." 

"For the complete combustion of olefiant gas, it is 
necessary to mix the gas with five times its volume of 
oxygen : three only are consumed. If less be used, part 
of the carbon escapes combination, and is deposited as a 
black powder. It is clear, therefore, that the whole of 
the hydrogen of any of these compounds of carbon may 
be combined with oxygen, while a part of their carbon 
may escape combustion, even when enough oxygen is 
present for its saturation." 

"That which takes place when the mixture is de- 



78 COMBUSTION CHEMICALLY CONSIDERED. 

signedly made in the most perfect manner must, un- 
doubtedly, arise in the common processes of combustion, 
where the mixture is fortuitous and much less intimate. 
Any method of insuring the complete combustion of 
fuel, consisting partly of the volatile hydro-carbon, 
must be founded upon the principle of producing an inti- 
mate mixture ivith them, of atmospheric air, in excess, 
in that part of the furnace to which they naturally 
arise. In the common construction of furnaces, this is 
scarcely possible, as the oxygen of the air, which passes 
through the fire-bars, is mostly expended upon the solid part 
of the ignited fuel with which it first comes in contact." 

In view of the foregoing opinions from Prof. Daniels, 
it is clear, that some better device is needed at furnaces 
than we have yet had, by which air or oxygen may be 
taken into the combustion-chamber, as well as through 
the grate-bars or fire, especially for bituminous coal, if 
we would utilize the gaseous elements of the fuel ; and 
any device that will effect the most intimate mixture of 
these gases with the oxygen of the air, will be most 
successful in securing perfect combustion. 

We have many convincing illustrations of what nature 
requires, showing the importance of bringing air to 
the gases to effect perfect combustion, of which the 
common candle and Argand burner lamp are fair samples. 

Mr. Brande observes, "In a common candle the tallow 
is drawn into the wick by capillary attraction, and there 
converted into vapor, which ascends in the form of a 
conical column and has a temperature sufficiently ele- 
vated to cause it to combine with oxygen of the sur- 
rounding atmosphere, with a temperature equivalent to 
a white heat. But this combustion is superficial only, the 
flame being a thin film of white-hot vapor, enclosing an 
interior portion vihich cannot burn for want of oxygen. It 
is in consequence of this structure of the flame that 



COMBUSTION CHEMICALLY CONSIDERED. 79 

we so materially increase its heat, by propelling a current 
of air through it by means of the blow-pipe." 

Dr. Reid says, "The flame of the candle is produced 
by the gas formed around the wick acting upon the 
oxygen of the air; the flame is solely at the exterior por- 
tion of the ascending gas. All without is merely heated 
air, or the products of combustion; all within is uncon- 
sumed gas, rising in its turn to affect (mingle with) the 
oxygen of the air." 

Berthier, Vol. I., p. 177, observes, "The flame presents 
four distinct parts, namely: 1. The base, of a sombre 
blue ; this is the gas that burns with difficulty, because it 
has not yet acquired a sufficiently high temperature. 
2, An interior dark cone; this is combustible gas highly 
heated, but which does not burn, because it is not mixed 
with air. 3. The brilliant conical envelope ; in this part, 
combustion takes place with a deposit of carbon. 4. A 
conical envelope, which gives but little light surrounding 
the whole flame, extremely thin or attenuated; combus- 
tion is complete in this part, and it is at its contact with 
the luminous envelope that the temperature is highest." 

Another author says of the flame of a candle: "At 
its base we perceive a small part of a deep-blue color ; 
in the middle is a dark part which contains the gas 
evolved from the wick, but which, not being yet in con- 
tact with the air, cannot bum; outside of this is the 
brilliant part of the flame. We also perceive on the con- 
fines of this latter a thin, faintly luminous envelope, 
which becomes larger towards the summit of the flame. 
It is there that the flame is hottest." 

Dr. Thompson, in his work on Heat and Electricity, 
and other writers, give similar illustrations of the com- 
bustion of the gas in the flame of a candle; all of which 
point to an instructive lesson, much neglected in prac- 
tice, and proves conclusively the necessity of inter- 



80 COMBUSTION CHEMICALLY CONSIDERED. 

mingling air with inflammable vapors for the purpose 
of their combustion, as shown in the every-day occur- 
rence in the flame of a tallow candle or common oil 
lamp. 

It also proves that, although this flame be in contact 
externally with a current of air created by itself, yet a 
large portion of the tallow and oil passes off unconsumecl, 
with great loss of heat and light. A similar waste is 
constantly going on in furnaces on a large scale. 

All the authorities quoted agree on the main facts : 
Eirst, that the dark center of the flame is unconsumed 
gas ready for consumption, and only waiting to get into 
contact with the oxygen of the air. Second, that the 
portion of the gas in which the due mixing has taken 
place, forms but a thin film on the outside of such uncon- 
sumed gas. Third, that the products of combustion 
form the transparent envelope (which may be perceived 
on close inspection). Fourth, that the collection of gas 
in the interior of the flame cannot burn for vmnt of 
oxygen. 

These points involve the whole case of the furnace, 
and illustrate the difference between imperfect and per- 
fect combustion. It shows that, although the bodies of 
gas and air apparently have free access to each other, yet 
combustion is incomplete because time is wanting for 
their due mixture. Thus combustion proceeds accord- 
ing to the uncle viating laws of nature, and only as the 
constituent atoms of gas get into contact with equiva- 
lent atoms of atmospheric ox} r gen.* 

If, then, the unrestricted access of air to this small 



* " In looking steadfastly at flame, the part where the combusti- 
ble is volatized is seen, and it appears darker, contrasted with the 
part in which it begins to burn, that is, where it is so mixed with air 
as to become explosive." — Sir Humphrey Davy. 



COMBUSTION CHEMICALLY CONSIDERED. 81 

flame by the laws of diffusion is not able to form a due 
mixture in time for ignition, it is clear that it cannot do 
so when the supply of air is restricted and that of the 
gas is increased. 

In the Argand lamp, the air being partially under con- 
trol and made to pass through a circular wick that is 
augmented, so that more gas is consumed within a given 
space than in the ordinary lamp; but why? Evidently 
because more opportunity for mixture is afforded through 
a series of jets or accessible points of contact. If the 
appertures through which air is admitted into the inte- 
rior of the flame be closed, the appearance of the flame 
is changed — part of the supply of air being cut off, it 
extends further into the air before it meets with the oxy- 
gen necessary for its combustion. 

Here we trace the imperfect combustion to the inade- 
quate mixing — within a given time — of the gas and air 
until too late, or until the ascending current has carried 
them beyond the temperature required for chemical 
action ; the carbonaceous constituent losing its gaseous 
quality, assumes its former color, and we have black 
smoke. Observing the means by which the gas is effect- 
ually consumed in the Argand lamp, it is evident that, by 
any device by means of which gas jets in a furnace could 
be presented to a sufficient quantity of air — as it is in 
the lamp — the result would be the same. 

The difficulty of effecting such a distribution of gas by 
means of jets in a furnace is well-nigh impossible; but 
since the gas cannot be introduced to the air, may not 
the air be introduced by jets into the gases. How to do this 
successfully is the great problem to be solved in burning 
coal (especially soft coal) economically. This has been 
attempted, both in this country and Europe, with more 
or less success. 

One of the most successful experimenters in this 



82 COMBUSTION CHEMICALLY CONSIDERED. 

direction, who has given the result of his experience to 
the world, is Mr. C. W. Williams of England, to whom 
the writer is indebted for much of the contents of this 
paper. In a letter to Mr. Williams, Prof. Brand, in com- 
menting on his experiments, uses the following lan- 
guage : " Each jet of air which you admit becomes, as it 
were, the source or center of a separate flame, and the 
effect is exactly that of so many jets of inflammable or 
coal gas ignited in the air ; only in your furnace you 
invert this ordinary state of things, and use a jet of air 
thrown into an atmosphere of inflammable gas, thus 
making an experiment upon a large and practical scale, 
which I have often made on a small and theoretical scale, 
in illustration of the inaccuracy of the common terms of 
combustible and supporter of combustion, as ordinarily 
applied. In the one case (as in the Argand burner) the 
gas in the center meets the air on the exterior ; in the 
other, the air in the center, issuing into the atmosphere 
of gas, enlarges its own area for contact mechanically, 
thus increasing its measure of combustion. Thus we 
see that the value of the jet, or the method of taking air 
into the furnace through a large number of small aper- 
tures, arises in consequence of its creating for itself a 
large surface for contact, by which a greater number of 
elementary atoms of the combustible and "supporter" 
gain access to each other in a given time. 

Combustion, then, being a chemical process, depending 
upon the mixture of the gases with air in the right pro- 
portion, and as we cannot control the gases in a furnace, 
but can largely control the air : the question of perfect or 
imperfect combustion, as far as human means can be 
applied, is one regarding the air, rather than the com- 
bustible — the method in which it is introduced, as well 
as the quantity and quality supplied — the control also 
of atoms rather than of masses. 






COMBUSTION CHEMICALLY CONSIDERED. 83 

In this connection, it may be well to briefly allude to 
an erroneous impression that prevails in some quarters, 
that the hotter the fire — the more intense heat of the 
glowing coals — the more steam and power they get from 
a given amount of coal; also, that the gases are con- 
sumable by being brought into contact with a body of 
" glowing incandescent fuel." Yet any chemical work of 
authority would inform them of the well-established 
fact, that " decomposition, not combustion, is the result 
of a high temperature applied to the hydrogen gases — 
that no possible degree of heat can consume carbon — and 
that its combustion is merely produced by, and is in fact, 
its union with oxygen. 

" It is a palpable over-sight of this distinction that has 
led to that manifest blunder — the supposing that the 
coal-gas in a furnace is to be burned by the act of bring- 
ing it into contact with bodies at a high temperature;" 
or in the words of the patentees, by causing it to pass 
through, over and among a body of hot glowing coals. 

Indeed, those words of ^VV^att, "through, over and 
among," have led many astray, occasioned much waste 
of money, loss of time, and misapplication of talent. 

Such parties overlook the most important statements 
of Watt, in the same paper, viz., " and by mixing it with 
fresh air, when in these circumstances." The fact is, if 
the requisite air can be furnished and properly managed, 
the necessary heat for effecting combustion will never 
be wanting in the furnace. 



8± COMBUSTION PRACTICALLY CONSIDERED. 



SECTION II. 



COMBUSTION OF COAL 

PRACTICALLY CONSIDERED. 

In the preceding chapter combustion has been treated 
mainly with reference to its chemical relations, and the 
necessary conditions requisite to burning the gases in 
bituminous coal. We shall now briefly consider its 
application practically in the construction of steam 
boilers and furnaces. 

If we would economize fuel, we must give due atten- 
tion not only to mechanical appliances, but also to the 
nature of the bodies we deal with, their constituent 
parts and chemical relations respectively ; and as the 
laws of nature are inexorable, mechanical details must 
yield to those of chemistry. 

With this principle in view it will be found that the 
furnace, in which the operations of combustion are to 
be conducted, is of the first importance. General im- 
provements in the boiler and engines have been going 
on at a rapid rate, while scarcely any attention, until 
quite recently, has been given to the grates and the fur- 
nace. Even among engineers the notion too often pre- 
vails, that while every other appurtenance should be 
first-class, yet, " anything will do for a grate" that will 
stand up under hot fires. 

Hence the attempt to economize fuel and power is 
confined almost entirely to the boiler and engine and 
their mechanical proportions, while the grate-bars and 
furnaces have been neglected, which latter are the real 
source of economy and power. 



COMBUSTION PRACTICALLY CONSIDERED. 80 

It is not our purpose here to go into the comparative 
merits of the different kinds of boilers or grates, but will 
briefly touch upon some fallacies or old notions, the 
value of which seems to consist mainly in their ancient 
origin. Some place their main reliance on grate surface; 
others on large absorbing surfaces ; while a third demand, 
as the grand panacea, " boiler room enough" — without 
explaining what that means; and the requisites, in 
general terms, are summed up thus : — 

1. Sufficient amount of internal heating surface. 

2. Sufficiently roomy fire-box or furnace. 

3. Sufficient air space between the bars. 
\. Sufficient area in the tubes or flues. 
5. Sufficiently large fire-bar surface. 

All of which amounts to this : Give sufficient size to all 
the parts, and avoid deficiency in any. 

'* So gravely is this question of relative proportions 
insisted upon " — • says a popular writer on this subject — 
" that we find many treatises on the use of coal, and the 
construction of boilers, laying clown rules with mathe- 
matical precision, giving precise formulae for their 
calculations ; and even affecting to determine the work- 
ing power of a steam engine, by mere reference to the 
size of the fire-grate and the internal areas and sur- 
faces of the boiler ; yet in this apparent search after 
certainty, omitting all inquiry respecting the processes 
or operations to be carried on within them." 

One writer lays down the following dogmatic rules : 
" For every cubic foot oficater to be evaporated per hour, 
allow one square foot of grate-bar ; one square yard of 
heating surface; ten cubic feet of water space ; five 
square feet of water surface ; ten cubic feet of steam 
space." 

Says another writer, commenting on the above : 
; ' Here we have all the proportions laid down and 



86 COMBUSTION PRACTICALLY CONSIDERED. 

squared according to rule, as if it were the proportions 
of a building that were under consideration, rather than 
of vessels in which complicated chemical processes were 
to be conducted. These rules, however, will not teach 
us how best to effect the combustion of any given weight 
of fuel, or increase the generation, transmission, or 
absorption of any given quantity of heat. We have 
here laid down a scale of internal proportions, but no 
clue to that of the heat generative effect of a square foot 
of grate-bar, or the heat transmitting power of a square 
yard internal surface. 

" It may, indeed, be asked, what relation a square foot 
of grate-bar can have to a cubic foot of water ; or to any 
given weight of fuel? We know thafr under different 
circumstances, treble or quadruple the amount of these 
proportions may be beneficially or injuriously found in 
practice ; and that even double the weight of fuel may 
be more advantageously consumed on a given area of 
grate-bars, in one class of boilers, than could be effected 
in another. 

"In truth, the weight of fuel to be consumed has no 
legitimate relation to the space on which it may be laid, 
and depends on other considerations : viz., on the quan- 
tity of air passing through it, the time employed, and 
the weight of oxygen taken up by the several con- 
stituents of the fuel respectively. 

" Again it may be asked, what relation a square yard 
of heating surface has to the transmission of any given 
quantity of heat, or the generation of any given quan- 
tity of steam? These calculations, in fact, have no value 
except on the assumed, but utterly erroneous data, that 
each square foot of grate surface is equivalent to the 
perfect combustion of a given weight of fuel, and the 
generation of a given quantity of heat in a given time; 
and that every square yard of internal surface must, 



COMBUSTION PRACTICALLY CONSIDERED. S< 

necessarily, be brought into action and received as equiv- 
alent to the transmission of a given quantity of heat. 

" Now the magnitudes and quantities which here really 
require to be calculated are chemical, not mathematical. 
They are not those of flue-surfaces, or grate-bars, but 
of the bodies to be introduced to them, the quantities in 
which they respectively combine, and the heat evolved, 
applied, or lost." 

All boilers have their furnaces and grate-bars, on 
which the fuel is placed; their flues or tubes through 
which the flame or gaseous products pass ; and the 
chimney to obtain the necessary draught, and carry away 
the surplus or refuse products. 

The process of combustion is mainly carried on in the 
furnace; hence the kind and quality of the grate-bars 
upon which the fuel is to be burned, though oftenest 
neglected, are of the utmost importance. Next, a roomy 
ash-pit, to provide sufficient air and protect the bars. 
Third, sufficient area of combustion chamber. 

When all the conditions that belong to the introduction 
of air to the two distinct bodies to be consumed (the gas 
and coke) shall have been complied with, and systema- 
tized in practice, there ought not to be any more difficulty 
in securing perfect combustion in the furnace, than there 
is now in the common gas burner. To solve this prob- 
lem, however, instead of laying down inflexible rules of 
proportions of the mechanical apparatus to be employed, 
we must first consider what is to he done with said apparatus. 

In the combustion of bituminous coal, we have seen, 
there are two distinct bodies, the solid and the gaseous, 
to be dealt with. With regard to the proportions of the 
parts of the furnace, we have to first consider the super- 
ficial area of the grate for holding the solid fuel; second, 
the size of air spares, or proportional amount of space 
to the iron ; third, the means of keeping said air space 



88 COMBUSTION PRACTICALLY CONSIDERED. 

free from all obstructions to the draught ; fourth, the sec- 
tional area of the chamber above the fuel, for burning 
the gaseous portion of the coal and the introduction of oxy- 
gen to said chamber. 

As to the area of the grate-bars, as they are to support a 
solid body, no more area is required than the coal actually 
. covers at a uniform depth, and it is alone important that 
it be not too large ; while the area of the chamber above 
the coal, which is to be occupied by a constantly chang- 
ing gaseous body, it is important that it be not too small. 

With reference to the area of other parts of a boiler, 
no specific rules can be laid down with certainty, as the 
weight of fuel that may be consumed on any square foot 
of surface must depend on numerous other contingencies. 

As to the size of the grate, observation of the engineer 
will enable him to determine the proper length or width 
of the furnace : the important consideration being that 
it be confined within such limits that it shall, at all times, 
be vjell and evenly covpred with fuel. This is an essential 
and absolute condition of economy and efficiency ; yet in 
practice this condition is most often neglected. If the 
grate-bars be not uniformly well covered, the air will 
enter irregularly and rapid streams or masses pass through 
uncovered parts, and at the very time and places when 
and where it should be most restricted. 

Such a state of things bids defiance to all regulation or 
control of the supply of the air, upon which vie must depend 
entirely for perfect combustion and economy. 

The fire should not be allowed to run too low, as this 
would involve a loss of time and duty — the object being, 
of course, to obtain the greatest quantity of free-burning 
gases from a given amount of coal in a given time. 

A charge of coal being throAvn into a furnace, the heat 
from which the gas-generating process is effected is 
derived from the remaining portion of the previous charge, 



COMBUSTION PRACTICALLY CONSIDERED. 89 

then in an incandescent state. This demand for heat, 
however, is confined to the commencement of the opera- 
tion with each charge. The heat required for continuous 
gasification is, or ought to be, obtained chiefly from the 
flame itself; as seen in the case of a candle where the 
gasification of the tallow in the wick is derived from its 
own flame. Hence the importance of sustaining a suit- 
able body of incandescent fuel on the grate, particularly 
when a fresh charge is to be added to the furnace. 

We often hear complaints of the introduction of air 
being attended with decreased evaporation of water, or 
increased consumption of coal. These complainants 
should understand that in nearly all cases these results 
are due entirely to inattention to the state of the furnace, 
perhaps entirely due to the fireman leaving much of the 
grate uncovered, thus providing the shortest possible 
route for the introduction of double the volume that is 
required. 

The uneven condition of the fuel on the grate-bars often 
causes great alterations of temperature, by permitting 
an excess of air in irregular and uncontrollable quantities, 
through the uncovered portions of the grate; when the 
fire begins to burn in holes, the evil increases itself by 
the accelerated rapidity with which the air enlarges the 
holes for its own admission, causing a still more rapid 
combustion of fuel around the uncovered parts, at the 
very time when these orifices should have been closed ; 
hence the importance of keeping a uniform and even 
body of fuel on the bars, as well as the air spaces in the 
grate clean and free from ashes alike all over the grate 
surface. 

With reference to the thickness of fires to produce 
the best results, opinions differ; still there can be no 
question that the fires should never be so thick as to 
prevent the air from freely passing through the body of 



90 COMBUSTION PRACTICALLY CONSIDERED. 

fuel, and thus secure the proper mixture of the oxygen 
with the gases above the fuel, in order to obtain the 
most perfect combustion. 

This leads to a brief consideration of certain alleged 
improvements in the way of mechanical devices for 
agitating or " shaking " the whole grate surface at once, 
and thus keeping the fire clean without opening the 
doors to "slice "fires. While all that is claimed for 
" shaking" or " rocking " grates may never be realized, 
still it is safe to conclude, that with all the improvements 
that have been made in steam boilers and engines, there 
have also been some improvements made in grate-bars. 
By the usual method of cleaning fires with the "slice" 
bar, there can be no doubt that much fuel is wasted and 
steam lost, as well as injury done to boilers, by the rush 
of cold air against the heated surfaces when the fire 
doors are open ; hence any device, by means of which 
the above objections can be avoided, will not only pay 
on the score of economy, but greatly assist in the man- 
agement and control of fires. 

There are a number of movable or shaking grates in 
the market; but there are but two general principles or 
plans of construction : namely, the horizontal reciprocal 
movement, in which all the bars are moved at once in 
opposite direction each to the other, and lengthwise the 
furnace. The other a rocking motion of a series of bars 
or blocks running across the furnace. The first agitates 
or rakes the fire at the bottom only, sifting the ashes 
therefrom, and is always level whether in motion or at 
rest. The second has a semi-vertical motion, slightly 
opening and closing the air spaces. The latter must be 
handled with care — especially with fine fuel — or the 
upward motion will break up the fire too much and throw 
dust up the boiler tubes, and let good coal fall with the 
ashes. The best illustrations of these two general prin- 



COMBUSTION PRACTICALLY CONSIDERED. 91 

ciples are the so-called " Roller Grate " and the" Banister 
Grate." All others are but copies or partial imitations 
of these two leading principles, and like most imitations, 
fall short of the original in merit. 

In the light of what has been said on combustion, it 
will be seen that a practical "shaking" grate will 
supply some of the conditions requisite for getting the 
most heat and power from a given amount of coal, as by 
their use the fireman can carry a comparatively thin 
body of fuel distributed evenly over the grate surface, 
and free from holes. For by a slight movement of a 
lever — instead of the laborious effort with a "slice" 
bar — all the air spaces are cleared at ouce, without any 
waste of fuel, and a steady, even draught kept up, with- 
out loss of steam by opening the Are doors to " clean" 
fires. They also save injury to the boiler, caused by a 
rush of cold air to the heated surfaces while the fire-doors 
are open, thus causing sudden contraction, etc. 

The uniform and continuous supply of fresh air 
through the grate bars to the glowing coals, with the 
least interference to the necessary conditions for a suit- 
able mixture of the gases with the oxygen of the air, 
are the essential requisites for burning coal economically. 
A good " shaking" grate assists in providing these con- 
ditions. Besides the "shaking" grate, however, there 
is great need of some practical device for supplying air 
to the combustion-chamber above the coal — especially 
for bituminous or soft coal — to mix with the hydrogen 
gases and carbon which pass off unconsumed. This, 
added to a good shaking grate, combined with a good 
automatic damper regulator, will furnish conditions for 
combustion well-nigh complete and perfect. 

In burning anthracite coal or coke, the principal points 
requiring attention are, the selection of grate-bars that 
furnish the best distribution of air, through small jets, 



92 COMBUSTION PRACTICALLY CONSIDERED. 

to all parts of tlie furnace, and in sufficient quantity to 
effect a complete union with the gases, coupled with the 
necessary mechanical appliance for keeping them clean, 
so as to secure a uniform draught with the least inter- 
ference to steady combustion and loss of steam and fuel. 
A properly constructed " shaking " grate wilL best secure 
these results. 

Xext to this, the good judgment of the fireman is 
most important, who, as a rule should carry a compara- 
tively thin body of fire on the grate-bars, evenly distrib- 
uted over their whole surface, so that the air can freely 
pass through the incandescent fuel and supply the gases 
with the proper amount of oxygen to effect their combus- 
tion. The fire should be kept level and free from holes, 
as the admission of large masses or streams of air has a 
cooling effect, and retards the generation and combustion 
of the gases. 

The volume of air required for the combustion of the 
coke of a ton of coal (independently of the gas) may be 
easily determined, as in such a case there is but one 
combustible (the carbon) to be considered; and but one 
supporter (the oxygen) of the air. Therefore, any diffi- 
culty that may arise in practice is not a chemical one, 
but the result of some imperfection in mechanical appli- 
ances. While air is the main ingredient in combustion, 
it can be introduced in such a way as to quantity and 
method as to become a detriment, a fact often overlooked 
in practice. 

One writer observes : "If chemistry did not teach us 
that the rate of combustion produced in the furnace is 
dependent on the quantity of air passing through it, every 
day's experience would soon convince us of this." 
Again, the same writer observes : " This being the case, 
the matter stands thus : the quantity of heat generated 
is dependent upon the quantity of air admitted. So 



COMBUSTION PRACTICALLY CONSIDERED. 93 

also is the quantity of steam produced dependent upon 
the greater or less intensity of the fire." Another writer, 
commenting on the above, justly remarks: "Neither 
chemistry nor experience justifies these inferences. The 
quantity of heat generated is dependent on the relative 
weight of hydrogen first, and carbon afterwards, chemi- 
cally combined with their equivalent weights of atmos- 
pheric oxygen. The quantity of air admitted may, 
indeed, actually diminish the quantity of heat generated. 
So the steam produced does not depend on the intensity 
of the fire, but on the quantity of heat absorbed;" and 
both chemistry and experience agree with this latter 
statement. Were there nothing to be considered in the 
use of coal but the combustion of the fixed carbon, noth- 
ing would be required but the supply of air through the 
grates to the fuel in proper quantity. In the use of coal, 
however, the gas, also, is to be generated and consumed, 
and any excess of air or its injudicious introduction, 
though it might not affect the combustion of the carbon, 
may materially interfere with the quantity required for 
the gas. 

Now, as regards the quantity of air chemically re- 
quired for the coke or fixed portion of the coal, after 
the gas has been expelled. It can be shown that every 
6 pounds of carbon requires 16 pounds of oxygen. The 
volume of atmospheric air which contains 16 pounds of 
oxygen is estimated at 900 cubic feet, at ordinary tem- 
perature ; and as bituminous coal contains about 80 per 
cent of carbon, we have 1,600 pounds of coke (the pro- 
duct of 2,000 pounds of coal) requiring its equivalent of 
oxygen, which will be equal to 240,000 cubic feet of air. 
This great quantity of air required for the exclusive use 
of the coke on the bars must be passed upwards from 
the ash pit, the product being transparent carbonic acid 
gas of a high temperature. The carbon remains quies- 



94 COMBUSTION PRACTICALLY CONSIDERED. 

cent and without combustion (irrespective of the tem- 
perature to which it may be raised) until each atom shall 
successfully obtain contact and combine with its equiva- 
lent of oxygen, which becomes, as it were, the wings by 
which it is literally carried away in the shape of carbonic 
acid. Of itself, and without the aid of such wings, it 
has no power of movement, escape or combustion. 

The principal point requiring attention in supplying 
the coke or solid carbon with air — as already noticed — 
is preserving a uniform and sufficient body of fire on the 
bars, so as to prevent the air passing through in masses 
or streams, by which a cooling effect would be produced 
injurious to the generation of gas. 

The quantity of air required for burning the coke in a 
ton of coal having been considered, we now enter a 
more difficult field of inquiry, namely : to determine how 
much air is required for the gas of the same. It has 
been shown that for each cubic foot of gas, the oxygen of 
ten cubic feet of atmospheric air is required. In the 
process of making gas, it is understood that 10,000 cubic 
feet of gas are produced from each ton of bituminous 
coal, requiring no less than 100,000 cubic feet of air. 
Adding this to 240,000 cubic feet required for the coke, 
we have 340,000 cubic feet as the minimum quantity 
required for the combustion of each ton of coal, besides 
the excess which will always be found to pass beyond 
the chemical requirement. It is not likely that this large 
volume of air can, under any circumstances, all be intro- 
duced through the fire bars and fuel on the same. This 
would not only be contrary to all chemical experience, 
but involve a physical impossibility. It will be under- 
stood that a body of air can no more pass through a 
mass of incandescent coke, without being deprived of a 
large portion of its oxygen, than that the air can pass 
through the lungs of a human being and yet retain the 



COMBUSTION PRACTICALLY CONSIDERED. 95 

necessary quantity of oxygen to sustain life in another. 
For this reason (as well as others) there should be some 
other channel provided for the introduction of air to the 
gases, as the impossibility of supplying the requisite 
quantity through the grate bars is shown for the most 
complete combustion of bituminous coal; and as the 
means of obtaining the largest quantity of heat from 
a given amount of coal, turns mainly on the introduction 
of the air in proper quantity and the mixing of the same 
with the gases in equivalent proportions, the manner 
of its introduction becomes of prime importance. 

It has been stated (erroneously), that " the admission 
of air to a furnace should average from one-half to one 
square inch for each square foot of grate surface." 
Practice and experiment, however, prove that instead of 
one square inch, no less than from four to six square inches 
for one square foot of furnace is nearer the correct 
figures, the precise amount depending somewhat upon 
the gas-generating quality of the coal and the extent of 
the draught in each case. 

The discrepancies in estimates made by experimenters 
as regards the amount of air per foot of grate surface, 
may be accounted for by a neglect in estimating the 
velocity of the heated gaseous matter passing through 
furnaces to the chimney. It is not the egress or escape 
of intensely -heated products we are considering, but the 
ingress or introduction of air at the average atmospheric 
temperature and pressure, subjected to impeded motion 
from friction in passing through small apertures. The 
following table of relative velocities of the air on enter- 
ing will illustrate the joint influence of current and area 
of the air spaces : — * 

*The quantity of air passing through well-constructed furnaces 
may, in general, be regarded as double what is rigorously neces- 
sary for combustion, and the proportion of carbonic acid gener- 
ated, therefore, not one-half of what it would be were all the 
oxvsren combined. — Dr. Tire's Statement. 



96 



COMBUSTION PRACTICALLY CONSIDERED. 



Air aperture 
per sq. ft. of 
furnace for bi- 
tuminous coal. 


Velocity per 
second of in- 
gress current 
of air at 60°. 


Cubic feet per 

hour entering 

through small 

orifices. 


For every ton 

of coal in 

cubic feet. 


Square inches. 


Feet 
per second. 


Cubic feet. 


Cubic feet. 


6 
6 
6 
5 
5 
5 
4 
4 
4 


5 
10 
20 

5 

10 
20 

5 

10 
20 


7,500 
15,000 
30,000 

6,250 
12,500 
25,000 

5,000 
11,000 
20,000 


75,000 
150,000 
300,000 

62,500 
125,000 
250,000 

50.000 
100,000 
200,000 



Suppose a furnace measuring ten square feet of surface, 
with moderate draught, will be adequate to the combus- 
tion of two hundred weight of coal per hour, the gas from 
which would require 10,000 cubic feet of air. To supply 
that quantity within the hour will require the following 
relative areas of admission and velocity of current, viz. : 



Velocity of current per second 
of air entering the furnace. 

If at 6.66 feet per second, will require 
" 10. 

" 20. " " " " " 

" 40. " " 



Area of aperture in 
square inches per 

foot of furnace. 

6 square inches. 

4 

2 

1 " 



Thus the absolute necessity of ascertaining the prac- 
tical rate of current of the air when entering, before we 
can decide on the necessary area for its admission. Then 
again, the mode of introducing the air must not be over- 
looked, whether it is introduced through one or numerous 
apertures, — whether in a mass or divided form — has a 
great deal to do with effecting complete combustion, and 
the utilizing all the gas of the coal. Erom any point of 
view, it is evident that the manner of introducing air to 
the furnace, as well as the quantity required, becomes an 



COMBUSTION PRACTICALLY CONSIDERED. 97 

important consideration. The two bodies, the coke and 
the gases, are to be taken into account in the adoption 
of any mechanical appliance for introducing air or im- 
proving the draught and securing perfect combustion of 
all the elements of the coal. For bituminous coal, espe- 
cially, suitable means must be adopted for effecting com- 
bustion of the gases, to secure the best results in the 
generation of steam and obtaining the most power from 
a given amount of coal with facility and economy. 

Whatever the mechanical means may be, they should be 
arranged with the view of promoting a rapid diffusion or 
mixture of the air and gases. The irregularities in 
the generation of the gas in a furnace, and the con- 
stantly varying quantities to contend with, make it 
impossible to apply any inflexible rule which shall effect 
uniform results under all the varying conditions. The 
difficulties of regulating the admission of air by mechani- 
cal means, as to quantity, quality and mode for a suitable 
mixture of the air and gases, are obvious. The varying 
circumstances of land and marine boilers, of quick and 
slow combustion of large and small furnaces, the irregu- 
larities of the draught in different furnaces, and even in 
the same furnaces of the same boiler — considering, also, 
the various methods of firing and the uncertain qualities 
of the fuel used : all these and other unforeseen conditions 
render the theory of regulating the admission of air in 
accordance with mathematical calculations or rigid rules, 
mechanically applied, impracticable. Yet, such appli- 
ances are worthy cff careful examination, and may be of 
great aid under the control of a competent engineer or 
fireman in the economical management of a plant. 

It has been demonstrated by a great number of experi- 
ments, that to effect the perfect combustion of all the 
combustible gases produced in a furnace, a large demand 
for air (distinct from the air entering through the grate) 

7 



98 COMBUSTION PRACTICALLY CONSIDERED. 

always exists. Also, that, by entirely excluding the air, 
smoke is produced and heat diminished in all states of the 
fire : hence, if correctly assigned proportions of air and 
gases and their due mixture are once ascertained, the 
attention on the part of the fireman is simplified, and far 
less required in regulating the admission of air. Among 
the many experiments that have been made and improve- 
ments devised for admitting the air to the gases through a 
hollow bridge-wall opening in the sides of the furnace, 
or perforated plates inserted in the boiler front or else- 
where, we know of none more successful than those of 
Charles W. Williams, brought out through patient study 
of the subject, and numerous experiments under the name 
of the " Argand Furnace," a number of years ago. 

At the time, these experiments and devices attracted 
the attention of Sir Kobert Kane (one of the highest 
chemical authorities of the day), who examined Mr. 
Williams' improvements and made an exhaustive report, 
which we here reproduce. 

" The conclusions to which we have arrived, and which 
we believe to be established by very decisive evidence, as 
well of a practical as of a theoretical kind, may be briefly 
expressed as follows : — 

' k 1st. That in the combustion of coals a large quantity 
of gases and inflammable materials given out, which, in 
furnaces of the ordinary construction is in great meas- 
ure lost for heating purposes, and gives rise to the 
great body of smoke which, in manufacturing towns, 
produces much inconvenience. 

" 2d. That the proportion which the gaseous and vola- 
tile portion of the fuel bears to that which is fixed and 
capable of complete combustion on a common furnace 
grate, may be considered as one-fourth in the case of 
ordinary coal. 



COMBUSTION PRACTICALLY CONSIDERED. 99 

" 3d. That the air for combustion of this gaseous com- 
bustible material cannot, with advantage, be introduced 
either through the interstices of the grate bars or the 
door by opening it. In the former case, the air is de- 
prived of its oxygen by passing through the solid fuel, 
and then only helps to carry off the combustible gases, 
before they can be burned ; and in the latter case, the air 
which would enter by reason of its proportionate mass 
would produce a cooling iufluence, and cannot conven- 
ientlv be mixed so as properly to support the combustion 
of the gases. 

' ' 4th. That the combustion of the gaseous materials of 
the fuel is best accomplished by introducing, through a 
number of thin or small orifices, the necessary supply of 
air, so that it may enter in a divided form and rapidly mix 
with the heated gases in such proportion as to effect their 
complete combustion. 

"5th. That in burning coke, or when coal has been 
burned down to a clear red fire, although the combustion 
on the grate may appear to be perfect, and little or no 
flame may be produced and no smoke whatever made, 
there may be a great amount of useful heat lost, owing to 
the formation of carbonic oxide, which, not finding a 
fresh supply of air at a proper place, necessarily passes 
off unburn ed. 

" 6th. That under the common arrangements of boiler 
furnaces, where there is intense combustion on theflre 
(/rate and but little in the flues, the difference of tempera- 
ture in and around the various parts of the boiler are 
greater; and consequently the boiler is most subject to 
the results of unequal temperature. On the other hand, 
when the process of combustion is spread through the 
flues as well as over the fire grate, the temperature re- 
mains most uniform throughout, and the boiler and its 
settings must be least liable to injury. 



100 COMBUSTION PRACTICABLY CONSIDERED. 

" 7 th. That the heat produced by the combustion of the 
inflammable gases and vapors from the fuel in flues or 
chambers behind the bridge must be considerable, and 
can be advantageously applied to boilers, the length of 
which may be commensurate with that of the heated 
flues." 

The writer, to further enforce these conclusions, goes 
on to describe the results of his experiments, made with 
boilers fitted up "with air-appertures (on Mr. Williams' 
plan)," namely, through the fire-doors, the boiler fronts, 
the bridge-wall and other devices for introducing air into 
the combustion chamber above the coal on the bars, in 
any suitable way to mix with and utilize the gases. 
These experiments are very instructive and were quite 
successful in accomplishing the end sought, namely : the 
burning of the gases, and the prevention of the smoke — 
in the latter even more successful, apparently, than any 
of the numerous " Smoke consumers" (?) of the present 
day, who, instead of giving due attention to the chemical 
principles and laws underlying combustion, which would 
aid them in devising means for preventing smoke, vainly 
imagine they can by mechanical means circumvent the 
laws of nature and burn smoke after it is produced. 

In concluding this subject, we will draw attention to 
the importance of not only permitting an ample supply of 
air to the furnace through the grate surface or ash-pit, 
but also the necessity of some simple means — especially 
in burning bituminous coal — of allowing a large quantity 
of air to enter through the door or boiler front, by means 
of numerous small appertures (or by other effectual 
means), and thus secure the increased heating power 
arising from the combustion of not only the coke gas, 
but the carbureted hydrogen gases in the furnace. 

From the many experiments and the experience of ex- 
perts and authorities on this subject of combustion, it 



COMBUSTION PRACTICALLY CONSIDERED. 101 

has been found, however, to be a matter of no special im- 
portance as regards effects, in what part of the furnace or 
flues air is introduced, provided, this oil-important condition 
be attended to — namely: that the mechanical mixture of 
the air and gases be continuously effected before the tem- 
perature of the carbon of the gas (then in the state of 
flame), be reduced helow that of ignition. This tempera- 
ture (according to Sir Humphrey Davy) should not be 
under 800° Fahr., since below that flame cannot be pro- 
duced or sustained. 

From all that has been said, we arrive at the following 
conclusions : First, that in the combustion of fuel there 
is but one body combustible to be dealt with, viz., the car- 
bon and hydrogen; and but one "supporter" required, 
the oxygen of the air. Second, that in combustion 
atmospheric air is the largest ingredient (yet it is the one 
to which, practically, the least attention is given, either 
as to quantity or control). Third, that both chemistry 
and experience teach that combustion depends, not so 
much on the quantity of air passing through the incandes- 
cent fuel, as on the iceight of oxygen which is taken up in the 
passage. In fact, the quantity of air passing through it 
may be destructive of combustion if improperly intro- 
duced and distributed and when in excess of the demand 
of the fuel. Fourth, the quantity of heat generated de- 
pends, first, upon the relative weight of hydrogen and 
carbon ; afterwards, chemically considered, their equiva- 
lent weights of atmospheric oxygen ; so also, the 
quantity of steam produced does not depend so much 
on the intensity of the fire, as on the quantity of heat 
absorbed by the water. Finally, that success in generating 
the most heat and steam, and consequently power, from a 
given amount of coal, depends upon a compliance with 
the necessary conditions to perfect combustion, which 
involves not only a theoretical knowledge of chemical 



102 COMBUSTION PRACTICALLY CONSIDERED. 

principles, but also a practical knowledge of the best 
methods of combining them with mechanical appliances, 
and the perfect mixing of the constituent elements with 
which we have to deal in strict accordance with the un- 
deviatins: laws of nature. 



THE THREE STATES OV WATER. lUo 



PHRT III. 



SECTION I. 



THE THREE STATES OF WATER. 

According to all chemical authorities, each atom of 
water is a compound of one equivalent of hydrogen and 
one of oxygen; and in dealing with its several states, 
we find it described — 1st. Crystalized (ice); 2d. Liquid 
(water) ; 3d. Gaseous or aeriform (vapor). 

Physically considered, the properties of water when 
in a state of ice resemble those of other solid bodies in 
this respect, that its atoms are in close contact, have 
strong cohesive powers, and are incapable of motion. 
In the state of liquid, immobility is changed to mobility, 
with a strong attraction among its particles. In the 
state of vapor, other changes occur : attraction and 
mobility yield to mutual repulsion and divergence. 

The presence of water (atoms) are found in almost all 
states and forms of matter by chemists, who sometimes 
find their presence a source of difficulty in their experi- 
ments. The quantities of heat inherent in water in each 
of its three states, in the general opinion of chemists, 
are: latent heat of ice 10°, of liquid 1-10°, and of vapor 
1,000°. The first two are supposed to be correctly 
ascertained by physical tests ; the last only by approxi- 
mation, to what cannot be accurately determined. Heat 
is divided into two distinct classes, latent and sensible : 
the former signifying the status of water as a liquid, 



104 THE THREE STATES OF WATER. 

and producing no thermometrical effect ; while the latter 
(sensible) exhibits its dynamic influence by its action on 
the thermometer or other bodies with which it is brought 
in contact if capable of conduction. 

If then, the maximum heat in ice be 40° latent heat and 
32° sensible heat, the inference would be, that each atom 
of the crystalized mass, on receiving an additional unit of 
heat, would have its statical condition changed ; and losing- 
its crystalized form, it would separate from the mass 
and become part of a fluid or liquid body. The same 
process would occur on its receiving a further unit of 
heat beyond what it is capable of retaining in the liquid 
state, and its status would then undergo, a further change 
and become gas or vapor. In both cases — the passing 
from a solid to the liquid, and from that to the state of 
vapor — we notice the remarkable changes which super- 
vene, exhibiting the peculiar characteristics of each. 

Although the property in elastic fluids of ''mutual 
repulsion" — the effect of which is termed diffusion — is 
generally recognized, it is also claimed that "vaporized 
bodies cannot be distinguished, on any scientific princi- 
ples, from permanent elastic fluids." Whatever may be 
the cause of this principle of mutual repulsion, it is the 
main element which, in opposition to gravity, forms the 
chief characteristics of all elastic fluids, and should not 
be lost sight of, as it forms the basis of those effects 
exhibited in the various combinations of heat with 
liquids of all descriptions, from water to mercury. 

Heat being applied to a body of ice, the cohesive 
property of the constituent particles is lost; the particles 
separating from each other, fall from the mass by the 
force of gravity and become a liquid. " Now, as the 
thermometric temperature of the ice was 32° and that of 
the liquid 32°, it follows that the entire amount of the 
heat communicated and by which the change was effected, 



THE THREE STATES OF WATER. 105 

must be considered in the latent state." If heat be con- 
tinued, such of the liquid atoms as may receive each an 
additional unit will then assume the vaporous form ; and 
as it had previously received its full complement of 
latent heat, this additional unit will consequently be 
sensible or available heat, and as such will act on the 
thermometer. 

The atom of ice may be represented thus : One equiv 
alent of hydrogen (H.), one of oxygen (0.) and one of 
caloric (C.) ; the liquid atom, one of H., one of 0., two 
of C. ; the vapor atom, one of H., one of 0. and three of 
C, or the union of one atom of the liquid unit with three 
units of heat, two of latent and one of sensible heat. 



106 VAPORIZATION. 



SECTION II. 



VAPORIZATION — WHAT IS VAPOR? 

This subject has engaged the attention of philosophers 
and chemists of high authority ; and yet there seems 
to be no general agreement of opinion respecting the 
theory of vaporization. The different writers have 
adopted such various methods of describing the pro- 
cess, and having made use of the term in connection 
with evaporation in a manner tending to confuse the 
mind and complicate the subject, so that much remains 
imperfectly understood respecting the effect of heat on 
and its connection with water. 

Without undertaking to settle the differences of the 
many able writers on this subject, we merely propose to 
present, in as brief and concise form as possible, the 
views of some of the leading writers, whose opinions 
have been accepted as authority, with the able review 
and criticism of Mr. Chas. W. Williams, who has 
treated the subjects herein presented in an elaborate and 
original manner, arriving however at entirely different 
conclusions in many important particulars.* This inquiry 
will embrace the following points : — 

First. What is vapor? 

Second. How and where is it formed? 

Third. What are its special properties? 

Fourth. In what does it differ physically and dynami- 
cally from water? 



*'* A treatise on Vapor Atorns, Heat, Water and Steam, embrac- 
ing new views of vaporization, condensation, explosion, etc.," by 
Charles Wye Williams. 



VAPORIZATION. 107 

Fifth. What are the relative proportions of latent 
and sensible heat? 

Sixth. What relation has vapor to electricity ? 

Strictly speaking, vaporization means the single process 
of converting atoms of a liquid into those of vapor. 
Numerous instances might be given of the misapplication 
of the term and the confounding it with others, 
especially with that of evaporation. 

Had writers concurred in any one theory or definition 
of vaporization, there would have been less confusion. 
Turner* says : "Vaporization is conveniently studied 
under two heads — ebullition and evaporation. In the 
first, the production of vapor is so rapid that its escape 
gives rise to visible commotion in the liquid. In the 
second, it passes off quietly." Another writer (Mr. 
Williams) observes: "That vaporization cannot be 
studied under either head is evident, seeing that vapor 
may be formed without ebullition or any visible commo- 
tion whatever ; and as to rapidity, — that being solely 
determined by the rate at which heat is absorbed by the 
liquid, — as much vapor will be generated in a given time 
by the same quantity of heat whether with or without 
ebullition. It may be broadly stated that neither ebulli- 
tion nor evaporation have any immediate connection 
with vaporization." Dr. Lardner gives a different ver- 
sion of the subject, viz. : " When a liquid boils, vapor is 
formed in every part of its dimensions, and more particu- 
larly in those parts which are nearest the source of heat ; 
but liquids generate vapor from their surfaces at all tem- 
peratures." . How vapor can be generated at the surface 
of a liquid without a further application of heat is an 
unexplained mystery. Equally so when it is said, 
" Vapor is formed in every part of its dimensions." In 
such a case, where is the heat to come from by which 



' Elements of Chemistry, " by Edward Turner. 



108 VAPORIZATION. 

the liquid atoms are converted into vapor, or how is it 
to arrive at the interior of a body of water? 

In a popular work on Steam,* we have an epitome of the 
almost universally received theory, which will serve as a 
sample of all. " When heat is first applied to a body of 
water, a rapid circulation of the fluid ensues. The water 
at the bottom being first heated and expanded, becomes 
lighter than the rest, rises to the top, and is replaced by 
the current of cooler water descending to receive in its 
turn a further accession. By and by small globules of 
steam, formed at the bottom and surrounded by a film of 
water, are observed adhering to the glass ; as the heat 
increases they enlarge ; in a short time several of them 
unite, form a bubble larger than the others, and detach- 
ing themselves from the glass, rise upwards in the fluid. 
But they never reach the surface ; they encounter the 
currents of water still comparatively cold, and, descending 
to receive from the bottom their supply of heat, shrivel up 
into their original bulk and are lost among the other 
particles of water. In a short time the mass of the 
water becomes uniformly heated ; the bubbles becoming- 
larger and more frequent, are condensed with a loud 
crackling noise ; and at last, when the heat of the whole 
mass reaches 212° the bubbles from the bottom rise with- 
out condensation through the water, swell and unite with 
others as they rise, and burst out upon the air in a copious 
volume of steam, of the same heat as the water from which 
they are formed, and pushing aside the air, make room 
for themselves," Mr. Williams, commenting on the 
above, makes some pertinent remarks, as follows : — 

1st. "Heating and expanding of the liquid are both 
here assumed without proof or inquiry. 

2d. " The water, becoming lighter, rises to the top and 
is replaced by the colder water. No sufficient reason, 



* "The Steam Engine," by John Scott Russell, F.Ti.S.E. 



VAPORIZATION. 109 

however, is given for this replacement. An ascending 
lighter body would necessarily remain at the top, as a 
cork would. 

3d. "Globules of steam never adhere to anything: 
they have no such power or property. It is only when 
reconverted into the liquid state that adhesion becomes 
available. 

4th. " Globules, either of water or air, remain always 
visible up to the surface. 

5th. " The idea of bubbles of steam being condensed in 
their ascent is wholly inadmissible and contrary to fact. 

6th. "As to the steam being of the same heat as the 
water from which they are formed : that is simply im- 
possible, unless by ignoring the effect of heat." 

This same writer goes on at length with the analysis 
and gives a more reasonable view of the process as 
follows: "Water, un distilled and unnltered, being put 
into a glass beaker, over an Argand burner, numerous 
small globules will shortly be seen adhering to the bottom 
and sides of the glass. These have been mistaken by 
many writers for new-formed vapor, and, as above stated, 
for globules of steam. They are, however, mere globules 
of air, invisible at first by reason of their minuteness, 
but becoming enlarged as the glass to which they adhere 
becomes heated, and further, increasing by accumulation, 
they become visible, and adhering to the glass with such 
tenacity (if the process be carried on gently) that they 
may even be touched with a fine wire and swayed from 
side to side before they are dislodged. These not un- 
frequently remain adhering to the bottom until ebulli- 
tion has begun to agitate the mass. That these globules 
have no relation to vapor is proved by the fact, that if, 
by being previously boiled and filtered, the water has 
been deprived of its air (of which it contains about two 
per cent), and if on being cooled the process be repeated, 
no globules will appear." 



110 VAPORIZATION. 

It has already been stated that atoihs of liquid becom- 
ing atoms of vapor by the addition of heat, their char- 
acteristics are entirely altered ; mutual attraction and 
mobility being changed to mutual repulsion and separa- 
tion, with an increase of volume to an extent which 
makes them lighter than the surrounding atoms of liquid. 

On these newly acquired properties depend the whole 
phenomena which steam exhibits. " Steam," according 
to Prof. Dalton, being "An elastic fluid like common air, 
and possessed of similar mechanical properties." 

On this Sir Robert Kane observes, "The particles of 
volatile bodies repel each other at all temperatures, 
until they occupy completely the space in which the body is 
contained, and exercise a pressure which is equal to the 
force of their mutual repulsion, and which is termed the 
elasticity of vapor." We here recognize the elements of 
divergence or diffusion, force and pressure in volatile 
bodies. 

An important question then arises, namely : whether 
atoms of vapor on their formation retain and exercise 
their several properties as an elastic fluid, while they 
remain in a body of water in which they have been 
generated, before and until their escape into the air. It 
would appear from the foregoing that a rigid inquiry 
into the process of the union of heat with liquids is 
necessary. 

As the change from the liquid to the vaporous state is 
the direct result of the union with further increments of 
heat, it is a matter of indifference from whence that heat 
may be derived, whether from above, as from the rays of 
the sun or temperature of the air, or from beneath, as 
when heat is artificially applied. 

When heat is applied from above, it is evident the 
upper or surface liquid atoms must be in absolute contact 
with the air which rests upon it; the heat radiating 
downward upon the atoms forming this surface, each 



VAPORIZATION. Ill 

will absorb one or more units of heat, converting it into 
a state of vapor with its properties of increased volume 
and levity intact. 

This is a clear case of vaporization. The atoms of 
liquid being converted into atoms of vapor, and being 
subject alone to the weight of the atmosphere, there is 
nothing to prevent the full development of their volume. 

The enlarged volume, arising from the difference 
between the states of liquid and vapor, has been esti- 
mated as the difference between a cubic inch and a cubic 
foot; or the bulk increased 1,728 times. Whether this 
estimate as to the enlarged volume'be reliable or not, it is 
clear that in the vaporization of this surface stratum 
being effected its atoms will rise into the air and be 
replaced by the next in succession until the whole has 
passed away into vapor. In this way, lakes or pools of 
water are sometimes vaporized, the ground dried and 
the atmosphere replenished with vapor, which in turn 
descends in the form of dew or rain. 

"We next examine the process when heat is artificially 
applied to the bottom of a vessel containing water. Here 
the liquid atoms forming the lowest stratum are spread 
upon the bottom (like a carpet) and nearest the source 
of heat; the absorption of the heat, the changes in the 
character and form of the liquid atoms, is the same as 
Avhen applied to the upper stratum ; except in the latter 
case each atom receives its heat direct from the source 
above it, while in the former case each liquid atom 
receives heat by conduction through the vessel contain- 
ing the water. Special attention however, is directed to 
the different conditions, as they involve the main feature 
of the theory here contended for. 

The surface stratum of liquid atoms on being vaporized 
rise in the air as a bird from the ground, or a balloon on 
obtaining the requisite levity, alone impeded by the sur- 
rounding pressure of the atmosphere; while the lowest, 



112 VAPORIZATION. 

or carpet stratum, have a new or different element and 
obstruction to contend with. They are not in contact 
with the light medium of air and a pressure of fifteen 
pounds to the square inch, but in a medium of water 
which has a density eight hundred and thirty times 
greater than that of air. The result is that an atom of 
vapor, generated at the bottom of a mass of water, has 
to force its way upwards through this dense medium to 
the surface before it can come in contact with the air. 

While the surface atoms on becoming vapor were 
enabled to expand, say 1,728 times that of their liquid 
volumes under atmospheric pressure, it is evident that 
those formed at the bottom must be^ influenced by the 
additional density and pressure of the liquid medium in 
which they are generated and through which they have 
to work their way. Besides, they not only had to ascend, 
but diverge and diffuse themselves by virtue of their 
mutually repellent principle. So numerous, however, are 
these vapor atoms and so rapid is their generation, that 
a portion of them are found reaching the surface and 
escaping into the air almost instantaneously after the 
heat has been applied. This has been fully demonstrated 
by experiment* in which we have visible and physical 
proof : — 

1st. Of the rapidity with which vapor is formed. 

2d. Of its diffusion and consequent homogeneous 
temperature throughout. 

3d. Of the identity in a dynamic point of view as 
an elastic fluid of the vapor thus formed and escaping 
after having passed through the liquid mass in each 
vessel, and also, 

4th. That it is vapor and not heated water that is 
seen rising through the water. 



*" Water and Steam: Vaporization, Evaporation, etc.," by C 
W. Williams, A. I. C. E. 



vapor: an elastic fluid. 113 



SECTION III. 



VAPOR: AN ELASTIC FLUID. 

The vapor of water all authorities admit to be an elastic 
fluid, with which is associated pressure or force.. The 
term elasticity, however, has no legitimate reference to 
such properties in connection with a single body, or with 
liquids or vapor en masse. The term elasticity is cor- 
rectly denned as "the force in bodies by which they 
endeavor to restore themselves to their previous position 
or form." When speaking of a sponge or a spring, this 
is intelligible ; but air and vapor are different bodies and 
must be considered as distinct substances. Both are an 
aggregation of separate bodies, each of which is endowed 
with a property of repulsion among the atoms of its kind, 
through which it becomes the element of what is termed 

V 

elasticity of the body. This should be borne in mind, as 
we direct the attention to the investigation of liquid, 
gaseous or aeriform masses. 

On this point Prof. Farraday observes : " We have but 
very imperfect notions of the real and inamate conditions 
of the particles of a body existing in the solid, the liquid 
or gaseous states ; bnt when we speak of the gaseous 
state as being due to the mutual repulsion of the particles 
or of their atmospheres, although we miy err in imagining 
each particle to be a little nucleus to an atmosphere of 
heat, or electricity, or any other agent, we are still not 
likely to be in error in considering the elasticity as 
dependent on mutuality of action." 

This bears directly on the question of unity, the 
term used in representing heat in vapor, and the mutuality 



114 VAPOR: an elastic fluid. 

Prof. Rankine says : "A perfect gas is a substance in 
such a condition that the total pressure exerted by any 
number of portions of it at a given temperature against 
the sides of a vessel in which they are enclosed, is the 
sum of the pressure which each such portion would exert if 
enclosed in the vessel separately at the same tempera- 
ture." Dalton's theory in reference to fluids of any 
kind : " ' Each such portion ' must have reference to each 
separate atom or particle." It is the same thing as to say, 
that "the pressure exerted by any gas or elastic fluid is 
the sum of the repulsive forces which the several atoms 
exercise when en masse." As each atom of vapor, then, 
represents a unit of heat and repulsive force, so the 
amount of heat or pressure must be the sum of the units 
exercising such force. Temperature and pressure, there- 
fore, are but co-efficients of the quantity and number of 
atoms present in any given space. The Professor's 
legitimate inference is, that " divergence or expansion 
is a property independent of the pressure of other masses 
within the same space." This is also in accordance with 
Dalton's law, "that each gas or elastic fluid enters as 
into a vacuum" 

Now the practical results of vapor is involved in this 
law governing gases and elastic fluids, and lead to the 
following questions : — 

1st. Is vapor an elastic fluid? 

2d. Has it the properties of other elastic fluids? 

3d. Does it exert those properties independent of 
other masses in bodies in the same space? 

Therefore the analogy between vapor and other elastic 
fluids should be ascertained. 

" The density of the air" according to the latest 
authority, "is the result of the pressure to which it is 
subject." The, air is an elastic fluid; that is, its bulk 



vapor: ax elastic fluid. 115 

increases and its density diminishes whenever the 
external pressure is wholly or partially removed. — Eng- 
lish Cyclopedia : "Air." 

Again: "The repulsive force of the particles of air, of 
which we know nothing but its effects, is a counter- 
balancing force from within to the pressure from without, 
and is greater or less according to the greater or less 
nearness of the particles. In other words, the elastic 
force of the atmosphere as distinguished from the 
superincumbent column of air." So of the vapor of water. 
As an elastic fluid, there is the repulsive force of its 
several atoms acting as a counter-balancing force from 
within to the pressure from without. We may then con- 
sider this mutually repellent action as being the direct 
source of what is called the pressure of the mass, and 
that vapor but follows the same general law of other 
elastic fluids when relieved from pressure from without 
(that is, the surrounding medium, whatever it maybe), 
its bulk increasing and its density diminishing as the 
external pressure is partially or wholly removed. This 
is precisely the case when the vapor particles, on their 
escape into the lighter medium of air, are removed from 
the denser medium of the water. 

The same authority acids : "As we ascend in the 
atmosphere, the superincumbent column of air becomes 
of less weight and the density becomes less ; that is, a 
cubic foot at the height of 1,000 feet above the ground is 
not so heavy nor does it contain so much air as a cubic 
foot at the surface of the earth." The same of vapor, 
as it rises from the bottom of the vessel (in which it is 
generated) to the surface and thence into the air. If 
the air presses equally on all sides and in all directions, 
why may not the same be said of the denser medium of 
the water acting on the several particles of vapor in it? 
The question of bulk then, is a question of quantity or 
number in given spaces, each particle, however, preserv- 



116 vapor: an elastic fluid.. 

ing its identity from the moment of its generation until 
it reaches the highest region of the air. Again: "The 
air having in itself a force which tends to separate its 
particles from one another, or to expand the whole bulk, 
but which grows less and less as the particles are more 
and more separated, that is, as the bulk increases." Now 
what is this force, which so tends to separate its particles 
from one another, but the mutually repellent property 
inherent in the constitution of the vapor atoms? As we 
know of no power in nature capable of producing this 
tendency of particles to separate or repel each other but 
electricity, we have but to substitute the elastic fluid 
vapor for that of air and the description is reasonable 
and the analogy is complete. 

When we speak of a body of water, filled or saturated 
with vapor, we may equally describe it as we do air, 
namely : as being that state in which " the elastic force 
on a square inch of the surface of the air arising from 
its own constitution just balances the pressure upon that 
square inch." In other words, as the state of equilibrium 
which just balances the pressure of the medium in which 
it exists, whether that medium be water or air. 

It is said that from careful experiments, it appears 
that air and all other gases, as well as vapors, and all 
mixtures of gases and vapors, obtain an increase of 
elastic force for every increase of temperature, and ex- 
pand, if possible, in the vessel that contains them. 

Throughout we find that increase of temperature is re- 
garded as the basis or cause of the several changes of 
pressure, expansion or elastic force. The imparting of 
heat, however, is one thing ; but the indicated tempera- 
ture or amount of heat, quite another. Temperature as 
shown by the thermometer is but the index marking the 
several changes as they are produced. Dalton remarks, 
"It appears tome as completely demonstrated as any 
physical principle, that, whenever any two or more gases 



vapor: an elastic fluid. 117 

or vapors are put together into limited space, they will 
finally be arranged each as if it occupied the whole space, 
and the others were not present." Now the strict appli- 
cation of this law is what is contended for here. If vapor 
be an elastic fluid, and endowed with all the properties 
common to its kind, why shall not this law be equally 
applicable to the vapor of water as to any other known 
vapor, each being "arranged as if it occupied the whole 
space and the others were not present." The whole 
question turns on this : whether the vapor of water acts 
the part of an independent gas, and retains its properties 
while in a medium of water, as others do. That it does so 
maintain its identity and individuality, can be as "com- 
pletely demonstrated as any physical principle can be." 
This may be considered self-evident from the re-appear- 
ance of the vapor itself rising, with all its properties, on 
being liberated from the water ; for we can make no 
distinction between the vapor arising from before or after 
the heat has been withdrawn. That gravity has nothing 
to do with the mixing and diffusion of gases or vapors in 
the medium into which they are introduced, was proved 
by Dalton in his reply to Priestly. 

It is stated that Prof. Graham investigated the phe- 
nomena of diffusion with extreme precision and determined 
that the diffusive volumes are inversely as the squares 
of the densities of the gases. Dalton says, " If a quan- 
tity of water freed from air be agitated with any kind of 
gases not chemically uniting with water, it will absorb its 
bulk of the gas." AVhy, then, shall not the same reason- 
ing and the same law be applied to the mixing and agi- 
tating of the elastic fluid, vapor, with water : why not say 
that, if a quantity of vapor be agitated with water, it 
will absorb or take up the bulk of the vapor. Now, in 
spite of opposite theories and prevailing opinons, this 
mixing by agitation of water and vapor will be found 
literallv and strictly true. 



118 HEAT AND EXPANSION OF WATER. 



SECTION IV. 



ON HEAT AND EXPANSION OF WATER. 

The prevailing theory on this subject is : that water, 
while still retaining its liquid form and character, absorbs 
"heat and expands in proportion to the quantity of heat 
absorbed up to the temperature of 212° — the amount of 
the expansion being equal to Y25o> or according to Dr. 
Ure, ^5 of its value. There are however, so many proofs 
that may be adduced in contradiction of this theory, that 
it may be considered at least an open question and will 
bear further examination. 

1st. With reference to the properties of compressi- 
bility and incompressibility. It is generally admitted that 
water is so little susceptible to compression that it may 
be considered practically incompressible. But as nearly 
all writers, while admitting the incompressibility of 
water, still insist on its expansibility, it may be well to 
refer to some of the recognized authorities and examine 
the grounds on which this theory is founded. 

It has been found by experiment that under a pressure 
of 2,000 atmospheres there was scarcely an appreciable 
amount of compression in water ; and what little there 
was may be reasonably attributed to the portion of air 
and vapor it contained. Dr. Lardner observes: "All 
solid bodies being gradually heated from the temperature 
of melting ice (32°) to that of boiling water and then 
gradually cooled clown from 212° to 32°, will be found to 
have exactly the same dimensions at the same tempera- 



HEAT AND EXPANSION OF WATER. 119 

tnre during the process of heating and cooling, the 
gradual diminution of bulk in cooling corresponding 
exactly with the gradual increase of bulk in heating. 
Glass and other bodies, gradually heated from 32° to 
212°, which undergo degrees of expansion of the solid 
corresponding to two degrees of the thermometer, is twice 
the expansion which corresponds to one degree, and so 
on, the quantity of expansion being multiplied in the 
same proportion to the degrees through which the tem- 
perature had risen is multiplied." This rule applied to 
liquid water is strictly analagous, as follows : The num- 
.ber of its atoms converted into vapor corresponding to 
two degrees of the thermometer is twice the number (and 
twice the volume) that corresponds with one degree, the 
number vaporized being multiplied in the same propor- 
tion to the number of degrees through which the ther- 
mometer has risen. Again, he observes: ' ; The force 
with which a solid dilates is equal to that with which it 
would resist compression ; and the force with which it 
contracts is equal to that with which it would resist 
expansion." This is simply action and reaction expressed 
in law, dilatation and compression being correlative 
terms. 

Now this correspondence in forces being a general law 
of nature, must be applicable to all bodies ; and what are 
the elementary constituents of liquid but bodies subject 
to the same law? 

Here we see how a positive law T in physics may be 
rendered negative or doubtful when applied to liquids, 
when an arbitrary application is resorted to in order to 
satisfy the theory of expansion. It is here inferred that 
the resistance to expansion as regards liquids is not 
commensurate to that of compression ; or, in other 
words, that action and reaction are (in this case) not 
equal and opposite. If these liquids be incompressible 



120 HEAT AND EXPANSION OF WATER. 

they must be inexpansible ; for if the resistance to com- 
pression cannot be overcome, neither can the resistance 
to expansion or dilatation be overcome. This idea 
would be more in harmony with nature's laws.* 

In his paper on expansion, it is shown that all writers 
concur in saying that vapor and air follow the same law 
as gases or vapors of all kinds. Pursuing this inquiry, 
Prof. Thomson remarks, that " Dalton and Lussac, by 
keeping the gases experimented on dry, were enabled to 
discover that all gases experienced the same augmenta- 
tion of bulk when subjected to. the same temperature. 



*In testing this recognized theory further with reference to 
conductibility and nox-coxditctebility, Mr. Chas. W. Williams, 
in his book on this subject, calls in question the recognized authori- 
ties; and after quoting extensively from such writers as Prof. 
Brand, Sir Robert Kane, Dr. Read, Dr. Ure, Prof. Graham and 
others, showing the harmony and uniform agreement in their theo- 
ries and "erroneous assumptions," — in regard to the " ascending 
and descending currents " which claim the " circulating currents " 
are the cause of the "uniform temperature of the mass," etc.,— 
goes into the subject very thoroughly and exhaustively, showing 
by logical argument and numerous experiments and illustration 
that the whole theory is an error, — unscientific and misleading, — 
confessing withal that he formerly readily adopted the same 
theories, being misled by the authoritative statements of previous 
writers on the subject. Mr. Williams finally sums up as follows : 
" That ascending and descending currents do ultimately prevail is 
certainly true; equally so that they are mainly imtrumental in 
effecting circulation, in which sense the theory was adopted." 
He adds: " Subsequent experience, however, distinctly proved 
that they have no reference to that homogeneity of temperature 
which prevails long before these circulating currents begin, and 
which are solely attributable to the action of ebullition." He further 
says: "In all these statements we see everything is assumed: the 
heating and expanding of the water, the ascending and descending 
currents, and the supposed contact of every particle of the water 
with the bottom of the vessel." The value of these experiments, 
as Mr. Williams himself remarks, " consists not so much in dis- 
posing of the theory of descending currents, as that it furnishes 
conclusive evidence both of the existence of the vapor in the 
water and its diffusive action throughout the mass." 



HEAT AND EXPANSION OF WATER. 121 

Hoping to find a similar coincidence in liquids, the sub- 
ject was pursued with great labor, forgetting, however, 
that the atoms of gases, vapors or other elastic fluids 
have no fourth state into which they may be resolved by 
additional temperature ; whereas liquid atoms, by heat 
alone, become virtually atoms of an entirely different class 
of bodies, and possessed of essentially different proper- 
ties — as different in fact as are the elements of Avater, 
oxygen and hydrogen, in their separate states as gases, 
and their combined states as liquid water." 

Baffled in the attempt, Thomson comes to the conclu- 
sion that "liquids differ from gases in this, that their 
expansibility is not uniform, but that the rate of expansion 
increases with the temperature and is, therefore, the 
greater the higher the elevation at which a given 
quantity of heat is added to them." He saw the difficulty 
of reducing the rate of expansion in liquids to the law 
which regulates that of gases. Yet by applying the law 
of the quantity of vapor present in any given body of a 
liquid, a sufficient solution of the rate of expansion 
would have arisen. This doubtless hereafter will be 
determined. 

Dr. Larclner remarks : "The same vessel will hold a 
greater quantity of cold than hot water. If a kettle filled 
with cold water be placed on the fire, the water, when it 
begins to warm, will swell and flow from the spout until 
it ceases to expand." If by expansion the enlargement 
of the gross bulk of the water only is implied, this is 
true enough. But such expansion is the result of 
elementary atoms being successively converted into 
vapor. In no other sense does the water swell. And in 
that sense it never ceases to swell all the time heat is 
applied until the point of saturation is reached. 

Again he says: "Since the magnitude of anybody 
changes with the heat to which it is exposed ; and since 



122 HEAT AND EXPANSION OF WATER. 

when subject to the same calorific influence, these dilata- 
tions and contractions, which are the constant effect of 
heat, may be taken as a measure of the physical cause 
which produces them . . ." This is doubtless correct when 
applied to individual bodies among which the constituent 
particles of liquids may be classed, but not to the aggre- 
gate of those bodies. Here lies the main source of error. 
If water were a body to be dealt with in bulk, as a ball 
of iron or lead, and capable of receiving and conducting 
from atom to atom successive increments of heat, with- 
out any change in its status of liquidity, we might, in 
such a case, correctly infer its expansion. But water, 
or indeed any liquid, has not that power or property of 
conduction among its constituent particles as metals or 
solids have, and consequently is incapable of expansion 
in the sense of such bodies. Besides, heat, that invisible 
and imponderable agent, knows nothing of the mass of 
contents in the vessel. It deals only with the individual 
atoms of which the mass is composed, whether liquid or 
solid, and with which it comes into contact. When, also, 
we consider how nature in its wonderful economy appor- 
tions the combining volumes, weights or other properties 
of matter, there can be no disproportion between atoms 
of liquids or solids, and units of heat. Their union is 
but part of the immutable law of nature stamped on 
matter of all kinds. Each atom has not only its specific 
duty to perform, but the faculty of performing that duty ; 
none will be tried and found wanting. The power of 
the wind is but the sum of the powers inherent in each 
individual atom. So of the waves, or a crowd of human 
beings. It is to these, then, and their respective proper- 
ties, to which our inquiries should be directed. 

As water or its constituent particles cannot undergo 
any change, physical or dynamical, without a sufficient 
cause, liquid particles at the temperature of 32° must 



HEAT AND EXPANSION OF WATER. 123 

continue at 32° until they have each received their 
equivalents of heat by which they lose their status of 
liquidity. They are then no longer liquid atoms, but 
absolute atoms of vapor. On what grounds, then, can we 
assume that liquid atoms are heated or expanded, and 
still retain their liquid form and properties? Such an 
hypothesis would be contrary to the evidence of facts. 

To say that water can be a recipient of heat and be 
expanded while it retains the liquid state, and is also a 
non-conductor of heat, would involve a physical solecism 
irreconcilable with reason and common sense. 

The oversight of the various authors who have written 
on this subject consists mainly : — 

1st. In ignoring the formation of vapor as rapidly as 
heat is applied. 

2d. In overlooking the existence of vapor atoms in 
the body of the water, and their diffusion throughout 
the mass. 

3d. In assuming the liquid atoms to be the recipient 
of the heat without any change in their status. 

4th. In overlooking that vapor atoms, being necessarily 
individually larger than the liquid atoms from which 
they were formed, fully accounts for the gross enlarge- 
ment of the mass. 

The writer, from whom we have made copious drafts, 
in treating this subject (and who is chiefly responsible 
for the views herein) has finally summed up the argu- 
ment in the following manner: "Correctly speaking, 
then, there can be no such thing as heated or expanded 
water or other liquids, even as regards mercury, which 
only follows the general law. 

In ordinary language and as a mere conventional term, 
we may speak of water being heated and expanded, and 
of having an increased temperature. When, however, 
we are treating the subject in a scientific point of view 



124 HEAT AXD EXPANSION OF WATER. 

and with reference to the strict nomenclature adopted 
by chemists, we should avoid whatever may be unwar- 
ranted as but tending to confusion, as this may lead to 
serious complications. Water may be spoken of as 
being mixed with vapor as with air, and its variations of 
temperature described. That temperature, however, 
should be attributed to its right source, namely : the 
quantity or number of vapor atoms then present in any 
given space, these being the true and only source of 
dynamic effect. 

On the w r hole, then, we have sufficient to justify the 
following: conclusions : — 

1st. That water, or other liquids, being incapable of 
compression, are equally incapable of expansion. 

2d. That water being a non-conductor of heat, must 
also be a non-recipient of it. 

3d. That as it cannot be heated or expanded and still 
retain its liquid form and properties, it cannot be ther- 
mometrically affected. 

4th. That its enlarged volume is attributable, not to 
any measure of expansion as a liquid, but to the presence 
of vapor in it, in a state of an elastic fluid. 

5th. That this condition is in entire accordance with 
the recognized laws of elastic fluids. 

The respective properties of liquid and vaporous atoms, 
as regards the changes they undergo bj f heat, from the 
liquid to the vaporous state, may be thus described : — 

LTQUID ATOMS. YAPOR ATOMS. 

1. Gravity. 1. Gravity. 

2. Latent Heat. 2. Latent and Sensible Heat. 

3. Mutual Attraction. 3. Enlarged Volume. 

4. Mobility, inter se. . 4. Increased Temperature. 

5. Non-Conductibility. 5. Mutual Repulsion. 

6. Incompressibility. 6. Diffusion or Divergence. 

7. Inexpansibility. 7. Conductibility. 

8. Negative Electricity. 8. Compressibility. 

9. Expansibility. 

10. Positive Electricity. 



HEAT UNITS; VAPOR ATOMS. 125 



SECTION V. 



HEAT UNITS; VAPOR ATOMS. 

More than a century ago Dr. Black announced his dis- 
covery in heat, and the laws have ever since been the 
subject of investigation and experiment. Since then, 
numerous writers have thrown more or less light on the 
phenomena of heat; " but the relations between the pres- 
sure, the density, the heat and the temperature, are yet 
undetermined and but very imperfectly understood." 
The common, but erroneous, theory that water becomes 
the recipient of heat, while still retaining its liquid form, 
and the assumption that the relations between the pres- 
sure, the density, heat and temperature are influenced 
by separate laws, are not calculated to throw much light 
on the subject. 

One writer says: ''Water retains its heat only under 
pressure. If the pressure be relieved, the heat, which it 
is then unable to retain, is carried off by the formation of 
steam, until the increasing pressure and the decreasing 
heat are again in equilibrium." Another writer (Mr. 
Williams) -very appropriately remarks : " With equal 
regard to fact might it be said that a pound weight of 
shot retains its heat only under pressure. In truth, pres- 
sure has no more relation to the chemical absorption or 
retention of heat by the atoms of water than by the 
grains of a body of shot. This theory appears based 
on the double mistake : first, of assuming water to be a 
body in the sense that we speak of a body of lead, rather 
than as an aggregate of separate bodies, say of a given 
weight of shot ; and secondly, that it is only when it can 
retain no more that the heat goes to the formation of 
steam." 



126 HEAT units; vapor atoms. 

Again it is said, " That pressure is maintained on 
water by its own steam." Were this the case, how are we 
to account for the formation and visible appearance of 
steam, from the moment the heat is applied, and while the 
temperature is raised but a single degree from the 
starting point? 

Now the uniformity of temperature that prevails in 
the water and above it, in close vessels, ought to be con- 
clusive as to a corresponding pressure, or, what is the 
same thing, a correspondence in the quantity of vapor in 
both places, in excess of saturation. If this were not so, 
Dalton's law of the " water acting the part of a vacuum 
to elastic fluids " would be erroneous. 

A certain number of degrees, 212, is said to indicate 
the maximum temperature of water under atmospheric 
pressure, but in exceptional cases it has been shown a 
much higher temperature may be reached without ebullition 
or any increase of pressure. Dalton correctly observes : 
" All bodies are constituted of a vast number of extremely 
small particles, or atoms, bound together by a force of 
attraction. Besides this we find a force of repulsion. 
This is now generally, and I think properly, ascribed to 
the agency of heat." So that we have to consider the 
matter of w T ater not in the mass, or as a single body; but 
as an aggregate of bodies, the constituents of which and 
their several relations to heat are the proper objects of 
inquiry. 

Therefore, w r e must consider the action of the smallest 
elementary portions of the one with the smallest portions of 
the other; and the inquiry into the constitution of .the 
matter of water, with reference to heat and temperature, 
should relate to the molecules or atoms, rather than to 
the mass. With these as independent bodies the heat 
has combined, and the result of such union is not that the 
whole body has been heated, but that such heat is con- 



HEAT UNITS; VAPOR ATOMS. 127 

tined to the individual particles affected and converted into 
vapor. We must not lose sight of the fact that a body 
of water or any liquid is as much, so far as practical 
results are concerned, an aggregate of individuals as 
an army or a multitude of people. 

We are not inquiring into the nature of heat, but into 
the effect physically and dynamically produced by its ab- 
sorption or union with the atoms of which water is com- 
posed ; therefore, in this case, as with all other descrip- 
tions of matter, " equivalent determinate quantities are 
essential in producing given results." We haA^e no reason 
to doubt that the same law applies to heat, in its com- 
binations with the matter of water. If we know the 
gaseous constituents of the elementary atoms of water, 
there can be no rational grounds for objecting to treat 
such atoms in their respective unions with heat. 

It may be said that, as heat is an imponderable element, 
we cannot speak of it as "atoms of heat;" yet, in a 
scientific inquiry into the relative quantities absorbed or 
brought into union with equivalent quantities of water, 
we are justified in speaking of it as in divided, portions. 
This is the common method of all writers on the subject, 
under the term "units of heat" (sometimes termed 
doses* ), as so many different increments of temperature. 
By this system of equivalent atoms in all combinations of 
matter we are enabled to decide chemically and physically, 
on atomic processes, and to understand how and why the 
air we breathe, and by which life is sustained, in its ele- 
ments is identical with that destructive compound, nitric 
acid, by which animal life would be instantly destroyed ; 
and that the onlv difference between these life-sustaining 



* " Most bodies are susceptible of three states of existence ; 
namely, solid, the liquid, and the elastic, or vapors ; and all these 
are effected by the introduction of different doses of caloric." 
— Bees. Cyc. Condensation. 



128 HEAT UNITS; VAPOR ATOMS. 

and life-destroying compounds is one of mere definite 

proportions or equivalents. Therefore we are justified in 
speaking of one or more units of heat in combination with 
one or more atoms of vapor ; and to understand the prop- 
erties of water in any of its states, in combination with 
heat, we must consider the mutual action of units of heat 
in the constituent particles or atoms of voter. 

Heat acts on and vaporizes the liquid atoms in the 
human frame in the same way and under the same im- 
mutable law as it does in liquids, in any form or phase. 

When the thermometer indicates 212° in liquids ( as in 
the blood in the animal econom}^ at 98° ) further incre- 
ments of heat are absolutely available, not as necessarily 
influencing or increasing temperature in the mass (which 
they could only do by remaining in it), but as generating 
further atoms of vapor : these, however, being no longer 
retainable by the laws of diffusion, and under mere at- 
mospheric pressure, rise, and escape as rapidly as they 
are formed, each carrying away its respective equivalent 
of heat. It is, then, not the quantity of heat that is in- 
fluenced by the pressure, but the quantity, or number of 
atoms of vapor in the mass which influences that pres- 
sure. Each individual atom of a liquid, when brought 
into union with an individual unit of heat, may be con- 
sidered as a distinct entirety, or substance, and no doubt 
bears a given relation to temperature, although impercep- 
tible by our powers of vision or measurement. 

These facts are well understood by chemists ; yet 
nearly all continue to regard liquids as separate bodies or 
integers, rather than as aggregates. These generalities 
must be abandoned, and we must look at water in its ele- 
mentary particles as we would at those of other descrip- 
tions of matter. The necessity for this mode of pro- 
ceeding will be more apparent when we consider that the 
quantities communicated are divisible into distinct 



HEAT UNITS; VAPOR ATOMS. 129 

classes, namely : latent and sensible, or more correctly 
speaking, statical and dynamical, the former being 
identified with the status of water as a liquid, and pro- 
ducing no thermometrical effect whatever ; while the latter, 
however limited may be the quantity, has its dynamic 
influence shown by its action on the thermometer, or other 
bodies (if capable of conduction) with which it may be 
brought in contact.* 

The foregoing analysis seems to warrant the conclu- 
sion that even the smallest quantity of water may, as a 
series of individual atoms, be vaporized and dissipated by 
proportional equivalents of heat, by which we are led 
to recognize the conversion of single liquid atoms into 
vaporizations as the only means by which each can obtain 
the buoyancy that enables it to rise and pass into the 
atmosphere. What takes place in vaporizing a single 
atom must be applicable in the case of millions consti- 
tuting a body or a single drop of water, and is but a type, 
illustrating the principle or process going on with water 
at the boiling point. 

The requisite equivalents of latent and sensible heat 
being absorbed by, associated with, or united to the liquid 
atom, its conversion into one of vapor is complete; and 
from the state of an inelastic body, with the property of 
attraction and mobility, it has assumed that of an elastic 
fluid with the opposite properties of repulsion and diver- 
gence. From this point of view, we are enabled to appre- 
ciate and apply Dalton's rule, that "the force and pressure 
of steam is the same in equal weights and at all temper- 
atures." In other words, that a grain of water, or a 
million of its atoms, when converted into vapor, will 
exercise the same " force and pressure " whether raised 
from a body of water at 32 or 212 degrees. By pro- 
ceeding in this way, we may logically infer that the temper - 



* For a full and exhaustive treatment of this subject, see Chas. 
W. Williams' work on Heat, Water and Steam. 



130 HEAT UNITS ; VAPOR ATOMS. 

ature and pressure must be in the ratio of quantity or 
number of atoms present in a given space, each represent- 
ing unity pressing, by the mere effect of accumulating 
numbers, the bulb of the thermometer, and producing a 
corresponding effect in the temperature. 

When therefore, we say vapor (or steam) is at the 
temperature of 212°, it cannot be supposed that the tem- 
perature of each atom is 212°. Were that the case the 
aggregate of heat imparted would, by accumulation, be- 
come inconceivable. We are then compelled to consider 
the indicated temperature merely as the sum of units then 
present. By this simple process the alleged anomilies will 
be disposed of, while the number or quantity present in each 
given space will be the measure of elasticity, pressure, 
force, volume and temperature, and the several other con- 
ditions incident to steam in mass. 

The misconception which souniversally prevails comes 
from looking in the wrong direction for the results of 
the heat applied : — 

1st. In assuming it to be chemically combined with 
the body of w^ater, instead of with those of its elementary 
atoms with which it comes into contact ; and 2d. 
Overlooking Dalton's well-established law that " vapors : 
elastic fluids " are but mechanically mixed with the liquid 
medium in which they may happen to be. 

Neglecting these two important considerations, we look 
to the body of the water, in its liquid form, as the chemi- 
cal recipient of the heat ; in the very face of the vapor 
which we see mechanically disconnecting itself from the 
w r ater, and thus carrying away that heat. Water, then, in 
the state of liquid, and at all temperatures, must be con- 
sidered as a mechanical compound of liquid and vapor 
particles. So also the boiling point, and the temperature 
of 212°, must be considered without reference to the 
water, but rather as irrespective of its presence, as if it 
merely represented a vacuum. 



EBULLITION AND CIRCULATION. 131 



SECTION VI. 



EBULLITION AND CIRCULATION. 

Having in a previous chapter described the phenomena 
accompanying vaporization, or the conversion of single 
atoms of liquid into those of vapor, and the peculiar 
repellent properties these atoms possess after such con- 
version, we will next consider the effect of a continued 
application of heat to water, and the process of ebulli- 
tion AND CIRCULATION. 

Ebullition has been so variously described by different 
writers that their accuracy may be reasonably ques- 
tioned. There are certainly some points that will not 
bear the test of examination. 

Says Mr. Williams: "In the first place, the general 
mass of a liquid does not boil." Ebullition, or boiling, is 
solely the local commotion which originates in the 
several groupings found at the bottom and then rising 
through the body of water. The bubbles (so often 
described) .are the mere aggregates of • the vapor atoms 
previously formed, although invisible. Inasmuch as they 
must exist before rushing to the points or projections 
of rough surfaces or motes accidentally presented to 
them, — as may be seen by watching the process of ebul- 
lition — just as the vapor atoms in the air must have 
previously existed before they could be grouped by the 
electric action, and descend in a shower of rain drops, as 
seen after a thunder storm (and possibly for the same 
reason). 

After quoting extensively from many writers on this 
subject, Mr. Williams says: "None of these writers 
refer to the true first cause or source of ebullition, 



132 EBULLITION AND CIRCULATION. 

namely, the presence of vapor in the water in excess of 
saturation, yet without this no groupings and, conse- 
quently, no ebullition can take place, as such does not 
begin until the quantity of vapor present approaches the 
point of saturation. 

This point, as already stated, will be reached when the 
diverging or self-repellent force of the vapor atoms 
throughout the mass, are in equilibrium with the con- 
verging pressure arising from the density of the water 
medium surrounding them. Now this equilibrium, of 
itself, demonstrates the pressure and influence of the 
vapor, since if the heat had been absorbed by the water 
or liquid atoms, these atoms, having no repellent prop- 
erty and being influenced by gravity alone, would rise 
and remain uppermost : consequently, uniformity of 
temperature throughout the mass could not exist. This 
point of saturation, commonly called the boiling point, 
will then be determined solely by the quantity of vapor 
present in any given space : in water it takes place when 
that quantity indicates the temperature of 212° \b"ahr., in 
alcohol 176°, in sulphuric acid 630°, and in mercury 660°. 
Let it now be assumed that 1,000 atoms of vapor in 
any given space is the saturating quantity in water : 
until that quantity be present there will be no tendency 
towards these groupings and no ebullition, nor even 
then unless there be some motes, points or foreign matter 
present." As the rise in the thermometer above 212° 
indicates the presence of vapor in excess of saturation, 
this may be physically demonstrated by the discharge of 
such excess, either gradually or suddenly, by the intro- 
duction of a heavy foreign substance — any «bocly that 
will fall to the bottom, such as pieces of coal, brick or 
iron, which serve as nuclei for groupings of the vapor. 

It would be interesting to follow Mr. Williams through 
the great number of experiments profusely illustrated 



EBULLITION AND CIRCULATION. 133 

in his work, by which he ascertained and fully demon- 
strated — 

1st. The existence of the vapor in water. 

2d. That the excess of such vapor beyond the 
saturating point may be discharged ' gradually or sud- 
denly. 

3d. That ebullition is the mere result (mechanical or 
electric) of the tendency of the vapor to rush into con- 
tact with any foreign matter that may be present and 
furnishing points or nuclei for aggregation. These 
small motes or points become nuclei, towards which the 
vapor will rush so soon as the saturating quantity shall 
be present, but not a moment sooner. These floating 
objects will cause the appearance of a continuous stream 
of aggregates or small globules. 

The aggregation of these atoms (already existing in 
steam) have been mistaken for its generation; and 
ebullition is merely accidental and has no reference to 
the generation of vapor and is solely the result of the 
aggregation of atoms previously formed, such aggregates 
being composed exclusively of such vapor atoms as are 
in excess of the saturating quantity. 

Ebullition being a fact, it must be in accordance with 
some wise provision of nature for a useful purpose. 
As it appears to have no direct influence in promoting 
vaporization, what then may be its practical value or 
effect in the economy of nature? At least two important 
objects may be inferred : 1st. The prevention of a 
useless, if not dangerous, accumulation of vapor in 
liquids, under, the accumulation of heat. 2d. The pro- 
ducing of that all-important movement of circulation — 
the element of equal distribution of heat and vapor 
throughout the mass. 

As regards the first, vapor cannot escape from a 
liquid, only at its surface : there would necessarily be an 



134 EBULLITION AND CIRCULATION. 

ever-prevailing tendency to its accumulation in the water 
were there no other means of effecting its discharge 
than would be due to the area of that surface under the 
mere operation of diffusion. 

Now this object is directly effected by the rapid collec- 
tion of the vapor atoms in the groupings which are seen 
in ebullition. As each group is formed by reason of its 
bulk and levity, it rises to the surface in the form of a 
globule, and with an accelerated force escapes into the 
air, the body of the liquid thus being relieved of its 
presence. Of the second purpose : When these groups 
and globules are produced, they rise with a force and 
momentum due to their enlarged volume and levity. 

These aggregates of the gaseous elements of vapor may, 
in their effect upon circulation, be compared to that of a 
balloon, mechanically forced upwards by the pressure 
from beneath of the heavier particles of the air. We 
know that the gas with which the balloon is filled, if 
liberated, would be discharged into the air, each atom 
ascending with a force due alone to its own specific 
gravity, but which would necessarily be slow and com- 
paratively ineffective. When, however, the myriads of 
atoms of gas are brought together and confined within 
the balloon envelope, the levity of the whole gives it an 
ascentional force and rapidity which carries it to the 
higher regions of the atmosphere. In the same way, 
each group of globules or vapor, formed at the bottom 
of a body of water, is productive of precisely similar 
results. The secondary and equally important result is 
that by which circulation is directly effected. As the 
balloon ascends, and on each step of its progress 
upwards, it would leave a vacuum below it (as a ship 
moving through the water behind it), were it not 
that the space is at once filled with the succeeding 
portions of the air (or water), and a mechanical action is 
produced. 



EBULLITION AND CIRCULATION. 135 

Circulation, then, is the result of quasi-induced cur- 
rents, consequent on the movement of a body through 
air or water, and in proportion to the rapidity of motion. 

The inferences here drawn — from these investigations 
and experiments, to determine the progress and influence 
of heat on matter and its motions — do not rest on any 
baseless hypothesis, but on a clear view of the constant 
and unerring laws of nature as far as they appear to our 
view or within the range of our reason. 



136 VAPOR IX WATER, ETC. 



SECTION VII. 



VAPOR IN WATER, AIR AND STEAM. 

Very few, if any, writers on the subject of elastic 
fluids recognize the existence of vapor in voter in its 
separate, independent character. It seems strange that 
the visible appearance of the great quantity that rises 
out of a body of so-called boiling or hot water should 
not have suggested the idea that it must, previous to its 
escape, have existed in the water ; and that without 
such separate and independent existence its volume 
could not have been enlarged, diffusion or divergence 
would have been arrested, pressure nullified and elas- 
ticity itself have ceased to exist. 

Atoms of vapor until affected by heat cannot be distin- 
guished in or out of water, by reason of their minute- 
ness ; yet we have sufficient evidence to convince us of 
their presence in both cases. While they remain apart, 
with their several diverging properties, they remain 
invisible; as soon, however, as they converge or con- 
gregate and form globules, they come within the reach 
of our senses. This may take place both in or out of 
the body of water. When in the water they form 
globules, which, by reason of their greater levity, rise to 
the surface, then burst and pass into the air above it; 
out of the water in a similar Avay, when they come in 
contact with and are surrounded by a film of liquid 
particles (these forming a visible envelope, producing 
what is called vesicular vapor) and appear in a- cloud. 

If vapor exists in the water, it may be asked, why it 
does not rise at once to the surface and pass away into 
the air, by reason of its greater levity than water. It 



VAPOR IN WATER, ETC 137 

may be asked with equal reason, why the vapor, which 
exists in the atmosphere near the earth, does not rise at 
once to the more rarefied upper regions and leave the 
lower without any? The cause and the reason are alike 
in both cases, and are found in the nature of vapor as an 
elastic fluid filling the entire space. The air and the 
water are but mediums (as regards density and pressure) 
in reference to either the upper or lower regions of the 
atmosphere, or the still lower medium of water ; the 
whole being but a question of degree, the vapor atoms 
being always in a state of mutual repulsion, without 
regard to the medium in which they may be formed. It 
is this diffusive action which prevents any permanent 
irregularity in quantity in any one portion, wiiether it be 
the atmospheric medium or a fluid of any kind. 

"Homogeneous elastic fluids," says Prof. Dalton, 
"are constituted of particles that repel one another with 
a force decreasing as the distances of the centers of the 
particles." This law of repulsion and relative distances 
being general, it is equally applicable to vapor or steam 
as to any other el astir fluid. This is placed beyond all 
doubt in his precise statements, which in substance are 
as follows : 1st. That vaporized bodies cannot, on any 
scientific principle, be classed in a distinct category 
from. permanently elastic fluids. 2d. That when two or 
more gases or vapors are put together, either into limited 
or unlimited space, they will finally be arranged each as 
if it occupied the whole space, and the others were not 
present. 3d. That they retain their elasticity or repul- 
sive power amongst their awn particles just the same in 
the water as out of it, the intervening spaces having no 
other influence in this respect than a mere vacuum. 

"This," observes Mr. Williams, -is practically the 
most important feature of Dalton's great discovery 
of diffusion, whether in reference to meteoroloaw or 



138 VAPOR IN WATER, ETC. 

physics — to temperature in the atmosphere or in the 
water, to the properties peculiar to the liquid or the 
vaporous state." 

We conclude, then, that with reference to varying 
degrees of indicative temperature, the quantity of vapor 
generated in or injected into a body of water, be it great or 
small, the repulsive power among its particles will cause 
them so to diffuse themselves that no part of the liquid 
mass shall be without its due proportion. Berth ollet 
demonstrated this law laid clown by Dalton — this inter- 
penetration or movement of gases, and called it diffusion ; 
and says: "In a mixture of gases, the pressure, or 
elastic force, exercised by each of the gases is the same 
as if it was alone." The question then arises, Is not this 
law equally applicable to the elastic fluid, vapor? The 
analogy is brought still closer by considering the gas 
(vapor) mixed with water. He says : " When a gas comes 
into contact with a liquid, the gas is absorbed in a 
quantity varying with the pressure to which it is sub- 
jected." Thus the constituents of the atmosphere are 
always formed in the water with which it is in contact; 
"and for the same gas, the same liquid, and the same 
temperature, the weight of gas absorbed is proportional 
to the pressure : that is, that at all pressures the vol- 
ume dissolved (mixed with it) is the same." Now, 
pressure, or the effect of diffusion, being the same, what 
is the amount of that pressure in water to which the 
vapor is subjected? This can only be determined by 
reference to the respective densities of the two media, 
the water and the air. Here then is to be found the 
true amount of effective pressure from without, to which 
every gas or vapor forced into or formed in water must 
be subject. 

This is still more clearly illustrated by Professor Silli- 
man when speaking of molecular repulsion, as follows : 
" If a definite volume of air is admitted into a vacuum of 



VAPOR IN WATER, ETC. 139 

twice that capacity, it does not, like a solid or liquid body, 
retain its original volume, but expands and fills the whole 
empty space; and the same offers a resistance when these 
particles are brought together by mechanical pressure. 
A similar resistance to compression is displayed in 
liquid and solid bodies." Here it is shown that molecular 
repulsion is equally referable to that of vapor or other 
elastic fluid, namely : in the force which acts repulsively 
among their particles. On the elastic force of heat, he 
adds : " Since the accumulation of heat causes the atoms 
of bodies to separate, and its removal causes them to 
approach each other, it must be admitted that whatever 
may be the nature of heat, it acts as a repulsive force " 
It is probable that this repulsive force cannot be explained 
on any other known principle than that of electricity. 
Bodies (atoms of vapor are bodies) in the same electri- 
cal state have a mutual repellent action. It is singular 
that this repulsive force is generally altogether ignored 
by writers when treating of vapor in water, although all 
admit it to be an elastic fluid and endowed with like 
properties. While all authorities admit the existence 
of vapor in the air, yet ignore it when in the denser 
medium of water, the prevailing theory would imply that 
it can exist in no other proportion than in the enlarged, 
expanded state, due to the pressure of the atmosphere. 

Dalton observes: " Yapor exists at all times in the 
atmosphere, and is one and the same as steam or vapor 
at 212° or upwards." Another writer remarks: "This 
goes far to confirm the case of unity of heat (as already 
explained), seeing how infinitely minute must be the 
equivalent of heat in each atom of vapor while in the 
atmosphere; and that 212° is merely the result of a 
given quantity or number of such accumulated atoms 
then present in space. Practically, then, there would 
appear a greater difficulty in conceiving the existence of 
vapor in the atmosphere than in water, seeing that air 



140 VAPOR IN WATER, ETC. 

is a positive refrigerator and conductor of heat, whereas 
we have no reliable grounds for saying that a liquid is 
the former, and we know it is not the latter." This same 
writer, quoting Dr. Henry (" This notion which gives 
identity to vapor formed by heat in vacuum is ingen- 
ious ; but how the vapor should ascend till it arrives at 
the air of the same density is not conceivable"), replies as 
follows : " Certainly not, so long as the heat is assumed 
to be absorbed by the water while still retaining its liquid 
form, and that vapor cannot co-exist with water in a 
separate and independent capacity. So soon, however, 
as these erroi s are repudiated, the ascent of vapor 
through the liquid mass will be as intelligible as the 
ascent of a cork from the bottom to the surface in a 
vessel of water. Here is the stumbling-block which has 
so long stood in the way ; yet, if we only look at the 
formation of vapor, not in the mass, but w^ith reference 
to its atoms, separately and successively receiving their 
quotas of equivalent units of heat, and obtaining their 
distinct properties of levity, repulsion and elasticity, all 
difficulties will be at an end." The last writer (Mr. 
Williams) who so ably defends this theory — namely, that 
vapor can and does co-exist with and in water in a 
separate and independent capacity — appears to fully 
demonstrate his proposition by a great number of 
experiments in his work on "Vapor in Water" and 
finally sums up in the following paragraph : — 

" So far from looking to what are called ' high authori- 
ties ' as safe, practical, experimental or scientific guides, 
we have in their writings on this question but a melan- 
choly array of contradictions and anomalies, from 
which practical men can find nothing on which they can 
rely, and are compelled to admit the necessity of experi- 
menting and reasoning for ourselves if we would avoid 
these discrepancies which embarrass both the subject 
and the student." 



EVAPORATION. HI 



SECTION VIII. 



EVAPORATION— ESCAPE OF VAPOR. 

Under the head of vaporization, the formation of 
vapor atoms from liquid atoms has been described. 
We will now consider the conditions under which these 
vapor atoms are separated and escape from the water. 

But for the inaccuracy in the use of language — which 
implies inaccuracy in reasoning — the distinction between 
the generation of vapor and its escape into the air would 
be obvious. Yet among writers of the highest authority 
the terms vaporization and evaporation are frequently 
used as synonymous terms, and so confounded and mis- 
placed as to lead to practical' errors. Notwithstanding 
the indiscriminate and careless use of these terms, there 
are no two processes in nature more distinct : vaporiza- 
tion being the conversion of liquid atoms into those of 
vapor by the absorption of heat ; evaporation being the 
11 mere escape of the vapor atoms so formed, and without 
reference to heat." As an instance of the misapplication 
of these terms: "Evaporation" says the Encyclopedia 
Britannica. "is that process by which water and liquids 
are converted into steam, an elastic fluid, and dissipated 
in the atmosphere." Here the cause is confounded with 
the effect. Water certainly is not " converted into steam " 
by evaporation. The term has no meaning but as 
expressing the escape or removal of vapor, and there 
can be no evaporation until there be vapor to escape. 
With equal propriety it might be said that the process of 
generating gas in the retorts by heat, is the same as 
that by which it passes through the pipes and escapes 
from the street burners. The generation and escape in 
both cases are equally distinct processes. Evaporation, 



142 EVAPORATION. 

then, is consequent of and subsequent to the previous 
act of vaporization; a neglect of which distinction 
involves the error of implying that liquid atoms are con- 
verted into vapor only when they rise and escape into 
the air. 

The Cyclopedia, in quoting the opinions of philoso- 
phers, upsets its own definition, as follows: "Aristotle 
ascribed the formation of vapor to the action of fire.." 
" Halley supposes small spheres of water to be filled 
with subtle fluid, so as to make them lighter than air." 
Desaguliers asserts that water is capable of being con- 
verted by heat into an elastic fluid much lighter than 
air. These authorities are correct in considering the 
formation of vapor to be the union of liquid particles 
with heat, but furnish no authority or intimation that 
evaporation means the imparting of that heat. One 
writer observes: "Evaporation, properly speaking, is 
the result, or rather effect, of the intimate union of 
elementary fire (heat) with water. By this union the 
water and fire combined form an elastic fluid, specifically 
lighter than air, and which is peculiarly distinguished by 
the name of vapor." Here we have a correct description, 
not of evaporation, but of vaporization, and it is only 
when the vapor thus formed escapes that evaporation 
begins. 

All admit that " evaporation produces cold," which is 
correct ; and since, as increased temperature is derivable 
from the increased quantity of vapor atoms present, so 
the escape of these atoms is the same as the escape of 
the heat which they (each) carried away, and by which 
the sensation of cold is produced. Eees' Cyclopedia 
says: "Cold is produced when any part of the human 
body is moistened with water and the same is suffered 
to evaporate." This is a direct case of evaporation : as 
the atoms of such moisture must first be vaporized 
before they can pass into the atmosphere. 



EVAPORATION. 143 

By a very simple experiment, vaporization and subse- 
quent evaporation can be demonstrated. Hold a cham- - 
pagne glass in the band, then pour in cold water (colder 
the better) ; a sensation of cold is immediately experi- 
enced, indicating a loss of heat from the hand. What 
becomes of that heat? The common opinion would say, 
that it had gone to heat the water: but this is an error. 
It has gone, first to heat the glass, and then, not to heat 
the water, but to vaporize or convert the atoms of the 
water, in immediate contact with the glass, into vapor, 
each atom of the liquid receiving its unit of heat, and so 
becoming one of vapor. What is the proof of such 
conversion? Namely, the escape of that vapor and 
becoming visibly condensed on a glass or mirror laid on 
or over the top of the glass. Here we have: 1st, the 
vaporization of a portion of the water, and 2d, the 
escape of that vapor and its visible condensation, which 
is tangible and conclusive proof. 

Of Spontaneous Evaporation. 

Unable to reconcile or account for phenomena of 
the escape of vapor at all temperatures, in the absence 
of any reliable explanation of place or means by which 
the vapor is formed, writers have recourse to the theory 
of " Spontaneous Evaporation." 

"Water slowly evaporates" (says Prof. Brande), 
"under exposure to the air; its vapor mixes with the 
surrounding atmosphere, and the process is usually 
called spontaneous evaporation : it takes place at all 
temperatures, and with a rapidity proportionate to the 
dryness of the air and the velocity of the current passing 
over it." " Here is an oversight of importance which 
merits attention " (says Mr. Williams). " The evapora- 
tion from water is here assumed to be in consequence 
of its exposure to the air. This is not the case; the 



14:4: EVAPORATION. 

evaporation, or escape of the vapor is always going on, 
whether the water be so exposed or confined in a vessel 
apart from the atmosphere. If we half fill a large 
bottle, and tightly cork it, we find the vapor continuously 
rising from the water, and being condensed on the upper 
part of the glass, always trickling down and again 
returning to the water, so that no loss of weight is 
sustained; while the lower part of the bottle, receiving 
heat from the temperature of the room, produces a con- 
tinuous supply of new vapor in the water," So there is 
no necessity for this recourse to a supposed " spontane- 
ous " action. The term seems to have been adopted as an 
excuse, by writers unable to assign a sufficient cause for 
the diminution of the mass of water exposed to atmos- 
pheric influence : it is, however, an unmeaning inapplica- 
ble term when thus applied to matter. 

All the movements in connection with evaporation 
are subject to the immutable and well-known laws of 
gravitation and diffusion ; and if we examine the subject 
carefully and experimentally, we shall find that the rise 
and escape of vapor atoms (which is virtually evapora- 
tion) is as much under the influence of gravity as that 
of a cork in water. The ordinary theory, however, 
leaves us to infer that vapor atoms only have an existence, 
as they rise from the surface of the water, and are then 
and there formed without any further accession of heat. 
In the light of the theory urged here, the expression 
"water evaporates" is incorrect, unless we add, "in the 
form and state of vapor ." This, however, involves the 
distinction between liquid and vapor atoms, and still 
leaves the question open : Where was the vapor before 
its escape, and how was it formed previous to its going 
off in evaporation? When this distinction is admitted, the 
difficulties of coming to an intelligent conception of this 
subject will be greatly diminished. The whole difficulty 



EVAPORATION. 145 

arises from considering the rise of the vapor from the 
surface of the water, apart from its previous existence 
in it. Of the fact of the vapor rising out of the water 
there can be no more conclusive evidence than physical 
test of its condensation. In this there can be no 
deception, as onr senses furnish absolute proof. 

It is found (by experiment) that there is a continued 
harmony " between the loss of vapor and the loss of 
temperature, which indicates a corresponding harmony 
between the weight and heat of each evaporating atom. 
Thus, in harmony with this theory, we are enabled, by 
observation and logical deduction, to arrive at accurate 
results, establishing a positive law, namely : that as 
each atom of vapor has its equivalent unit of heat, 
an increase or diminution in number of the one, 
must have its correlative in a commensurate increase or 
diminution of the other." 

44 A further result is necessarily deduced from this 
harmony of heat and quantity, namely, that of time, as 
the escape of this surface stratum will contain a smaller 
number of atoms : the result being that a commensurately 
longer time will be required in producing given amounts 
of evaporation — that is, given reductions on the gross 
weight of the body of water. Thus we see how the 
reduction of temperature must be the mere co-efficient 
of the loss of vapor." Dalton made some accurate 
experiments on these points, his attention being directed 
to the question of time rather than the corresponding 
differences in temperature and weight.* 



*" Water, freely exposed to the air, evaporates at all tempera- 
ures, even when in the state of snow or ice. The rapidity of 
evaporation is, however, much increased by warmth. Thus, in a 
calm atmosphere, Dalton found that when, from a certain surface, 
the evaporation from boiling water proceeded at the rate of 40 
grains per minute, it was 20 grains at a temperature of 180°, 13 
grains at 164°, 10 grains at 132°, and so on." — Herschel, in En- 
cyclopedia Brittanica . 



146 EVAPORATION. 

Numerous experiments have since been made, all 
establishing the fact that the loss of weight by evapora- 
tion, as it is the cause, so it must be commensurate with 
the loss of temperature — time alone being the varying 
incident in the process. Herschel says: ''Evaporation 
never takes place without the abstraction of heat from 
the evaporating surface." A mere truism. We may 
with equal truth say we cannot remove any portion of 
a body of water without an abstraction of a commen- 
surate weight : heat being as much an element of vapor 
as weight is of water. Water finally does not evaporate. 
but merely parts with its vapor. "In fact, the water — 
the liquid mass — has no direct action or influence on 
the process of evaporation, and is merely the denser 
medium in which, at the time, vapor happens to be ; and 
which, acting the part of a vacuum, gives scope and 
capability for its diffusion. Hence evaporation is the 
escape of vapor, also heat, which is the element of its 
existence as vapor." 



CONDENSATION. 147 



SECTION IX. 



CONDENSATION. 

" The term condensation is commonly applied to the 
conversion of vapor into water in the process of distilla- 
tion. The way in which vapor commonly condenses is 
by the application of some cold substance. On touching 
ft the vapor parts with its heat ; and doing so, it immedi- 
ately loses the proper characteristics of vapor and 
becomes water. If heat be withdrawn from steam or 
vapor, it no longer remains in the vaporous state, but 
resumes a liquid form. In this state it undergoes a 
great diminution of bulk, a large volume of steam 
forming only a few drops of liquid. Hence, the process 
by which the vapor passes from the aeriform to the 
liquid state, is called condensation." — Encyclopedia 
Brittanica. 

The above quotation is a correct description of the 
cause, process and effects of condensation, or the re- 
conversion of vapor into the liquid state. Applying this 
to the steam engine, the steam, owing to its elasticity, 
rushes into the condensor ; but what "cold substance" 
does it there meet? This is the important point to con- 
sider. For the almost universally received theory is, that 
the steam or vapor meeting a body of cold water, imparts 
its heat to the latter, and is thereby instantly condensed, 
or reconverted into the liquid state. This erroneous, 
but prevailing theory, arises from the assumption that 
water, although a non-conductor, is nevertheless an ab- 
sorber of heat, and overlooking the fact that water is not 



148 CONDENSATION. 

a substance to which vapor can give out its heat, or, 
which is the same thing, that heat is absolutely absorbed 
by water. If water coulcl convert vapor (as generally 
assumed) into the liquid state by abstracting its heat, 
the resnlt would be that vapor could not be formed, or, 
at least, would have no dynamic effect ; for the moment 
the first atom of the liquid was converted into one of 
vapor, by the heat, it would as quickly be reconverted by 
the mass of water surrounding it. No permanent condi- 
tion could exist, and no body of vapor could be formed. 
It is not possible to reject this logical inference. 

What really does take place " when vapor is thrown 
into what may be called an atmosphere of water, each 
atom is at once compressed or reduced in influence and 
prevented exercising its full expansive power by the 
combined densities of the two media — the water and 
air. No diminution, however, of the temperature of the 
vapor atoms follows. They merely remain, with their 
compressed volumes in the water, until they escape into 
the atmosphere, or by contact with some cold substance 
lose their heat, and are then bona fide reconverted into 
liquid form." Water, then, or any liquid, is not a sub- 
stance to which heat can be imparted; or, in other 
words, heat cannot be received and retained by liquid 
particles, each of which is susceptible to an instantaneous 
change in its statical or electrical condition, by the ac- 
cession of heat. It would be as reasonable to expect 
that atoms of ice coulcl receive or absorb heat, and 
having their temperature raised still retain their crystal- 
ized form (or state of ice), as that those of water could 
receive it and retain their status of a liquid. 

"Air is an elastic fluid," Mr. Williams " observes, 
" and is a recipient of heat, since its status cannot be 
altered by it, there being no fourth state into which it 
might enter by a further accession of heat. Besides, 



CONDENSATION. 149 

being also a conductor of heat, it is capable of receiving 
and imparting it to others, from atom to atom. In this 
way, the vapor in the atmosphere when brought into con- 
tact with a bod}' of colder air and more or less of the va- 
por atoms (according to the amount of atomic contact 
realized between them), gives out its heat to those of the 
air, returns to the liquid form, and produces the effect 
of visible clouds." 

When we consider the extreme miscibility of elastic 
fluids, or aeriform matter, and the extent of surface for 
mutual contact presented by the aggregation of the 
millions of atoms which compose bodies of air and 
vapor, we can readily account for the rapid condensa- 
tion of the vapor atoms in the atmosphere, when brought 
into connection or collision with currents of colder air. 
To these currents, then, may be attributed all atmos- 
pheric changes of temperature and humidity, from 
clouds, fogs and rain, up to the more rapid discharges 
accompanying electric disturbances. 

When we look into the changes in the electric condi- 
tion of these vapor atoms, on their losing the property 
of repulsion simultaneously with their loss of heat, and 
thereby becoming negatively electrified, we have the key 
to the intensity and great quantity of the electric fluid 
that is set at liberty. Looking at the subject from this 
point of view, we are led to conclude that the ordinary 
theory that cold water absorbs heat (in condensation) , 
thus reducing the vapor to a liquid state, — " annihi- 
lating it as vapor," — is an error; and until the true 
recipient of heat is determined, we must remain in the 
dark, to a greater or less extent, in regard to the princi- 
ple in which condensation is effected, and the best means 
of perfecting the process in the steam engine. 

The rapidity with which vapor parts with its heat 
furnishes strong proof of the views here presented — 
namely, of vapors being a mere aggregate of atoms, each 



150 CONDENSATION. 

of which has its unit of heat in combination, all being- 
capable of parting, at once, with their respective units ; 
for no matter how numerous these atoms may be, the 
result would be equally instantaneous : hence the impor- 
tance of the extended surface (or units of surface) for 
contact. 

In refutation of the theory of water condensation may 
be mentioned the fact, that when steam is injected into 
cold water (in a separate vessel) , instead of being con- 
densed or reconverted into water, it appears in the same 
visible, cloud-like form, as when the vapor is originally 
formed in the water. (See chapter on Vaporization.) 

If in this case the cold water converts the steam into a 
liquid state, how are we to account for its reappearance? 
Why does not the mass of water at once cool down 
(annihilate) or reconvert the first and succeeding atoms 
of vapor as fast as they are introduced? Facts like 
these, one would suppose, are enough to shake confi- 
dence in this condensing or annihilating theory. The 
fact that a small jet of steam discharged into a body of 
water is capable of almost instantly raising the whole 
temperature to 212°, shows conclusively that the process 
is not of liquification of vapor, bat, rather, of the satura- 
tion of the fluid medium with vaporous atoms. 

A comparison of the ordinary theory of condensation 
by water with Dalton's theory of diffusion would show 
that they are opposite and contradictory. Dalton's state- 
ment, now so generally endorsed, namely, " That steam 
is but dissipated and diffused through the water, as if it 
were a vacuum, and being an elastic fluid it retains its 
properties irrespective of such medium," seems to be in 
harmony with the facts. If the common theory is right 
(and Dalton is wrong), the steam would be at once 
annihilated by contact with the water. If Dalton is 
right, it would simply be diffused through the liquid 
medium, the same as if that medium were a vacuum. 



ON THE VACUUM. 151 



SECTION X. 



ON THE VACUUM. 

It appears, then, that according to the prevailing 
theory, steam, upon being brought into connection with a 
body of cold water, thereby becomes liquified or re- 
converted into water — in fact, is annihilated as steam, 
and that (as in the steam engine) the result of this an- 
nihilation necessarily produces a vacuum in the cylinder.* 
This theory (although endorsed and supported by the 
leading authorities from Watt, down), by the investiga- 
tions and experiments of Mr. C. W. Williams, has been 
pretty thoroughly ventilated, and, as we think, proven 
to be entirely erroneous. On this point Mr. W. says : 
" It certainly is not a desirable task to be anyway in- 
strumental in weakening so agreeable a reminiscence, or 
questioning anything coming either from Arago or 
Watt ; but in search after truth, however, and in justifi- 
cation of science, as no respecter of persons, it becomes 
necessary not only to question the truth of this particu- 
lar mode of concerting steam into water, but to charac- 
terize it as a misconception, if not an absolute fallacy." 

Whatever, then, may be the merit of the separate vessel, 
which is, in truth, the great element of Watt's success, 
the theory as regards the action of cold water in producing 
the vacuum, is altogether erroneous. 

No doubt the abstraction of the steam from the cylin- 
der naturally led to the conclusion that it had actually 
parted with its heat, and that it entered the cold water, 



* Professor Rankine says, "The ordinary condenser is a steam 
and air-tight vessel of any convenient shape, in which the steam 
discharges from the cylinder by a constant shower of cold water." 



152 OX THE VACUUM. 

and by condensation produced the desired vacuum. So 
far, however, from the steam losing its heat or being 
condensed into the state of water, is it not merely me- 
chanically diffused (as already observed on the Dalton 
theory) among its particles, in proportion to the respect- 
ive quantities of each? The cold water being (by means 
of the injector) dashed against or spread over the inner 
surface of the metallic condenser, the latter, becoming 
cold, acts the part of a true surface condenser, just the 
same as if the water had been made to act against the 
outside, as in the still. In this way, an absolute conver- 
sion of the steam into water is effective, and a vacuum 
produced in exact proportion to the extent of the avail- 
able surface and its reduced temperature ; and doubtless 
if the inside surface be sufficiently extended, and cold 
enough, the entire steam may be condensed, and & perfect 
vacuum formed. Practically, however, but a moderate 
portion of the steam is so disposed of. " That water," 
says Mr. Williams, " whatever may be its temperature, 
is incapable of reducing steam to its previous state and 
bulk of water, is susceptible of direct proof." He then 
goes on at great length and proves this by numerous 
experiments, and adds, "It may then be broadly and 
unequivocally stated that there is no other mode by 
which steam can be condensed — that is, reconverted 
into water — than by the abstraction of its heat by 
metallic refrigeration, as is done in the still or a system 
of metallic tubes " : That, in a word, there is none other 
than surface condensation. 

From the foregoing discussion, it is evident from the 
numerous extracts made that due consideration has not 
been given to the important distinction between vapor- 
ization and evaporation, and as to how and where this 
"invisible vapor" is actually formed seem to remain 
unsettled problems in chemistry. Why this is so may, 



ON THE VACUUM. 158 

perhaps, be accounted for by a lack of disposition, time 
to investigate for ourselves, or the habit of adopting the 
views of others without question or inquiry. In closing 
the subject under consideration, the following quotation 
is very appropriate and to the point : " If we trace the 
history of any science, we shall find it a record of mis- 
takes and misconceptions: a narrative of misdirected 
and often fruitless efforts. Yet, if amidst all these the 
science has made progress, the struggle through which 
it has passed — far from evincing that the human mind is 
prone to error rather than to truth — furnishes a decisive 
proof to the contrary and an illustration of the fact, 
that in the actual condition of humanity, mistakes are the 
necessary instruments by which truth is brought to light, 
or at least indispensable conditions of the process." 



154 ELECTKICITY. 



HPPENDIX, 



ELECTRICITY. 



The " conservation of energy" is an important law of 
physical science ; by which is understood, that for any 
manifestation of force in matter, there is or has been an 
equivalent force expended commensurate with the work 
done or new force developed. This law is recognized in 
all electrical phenomena, and, without the previous ex- 
penditure of energy, no electrical effects are produced. 

While we may not be able to determine the nature of 
electricity, we are forced to conclude that there is an 
inexhaustible supply of this subtle element in nature, 
always available for use ; and with an understanding of 
the laws governing the same and requisite mechanical 
appliances, we are able to collect this wonderful energy, 
control and direct its movements to the accomplishment 
of definite results. 

No electrical effect, however, can be produced except 
at the expense of some other form of energy. 

The progressive movement of electrical energy along a 
certain path is technically termed the "current," and 
the current in electrical parlance is always associated 
with the idea of motion. Just how or why this subtle 
element follows a definite path or " conductor " we do not 
know, but with the suitable apparatus we do know that 
it may be generated and directed in its movements and 
used to do our work. 



ELECTRICITY. 155 

The application of electricity for lighting and as a 
motive force is now so common that any one in charge 
of a plant should at least understand the meaning of the 
terms used by electricians in describing and operating 
electrical works ; therefore we furnish a brief description 
of the 



TECHNICAL TERMS. 

CURRENT, — In electrical parlance, is always associ- 
ated with the idea of progressive motion in some form. 
It is a form of electricity by which its energy and effects 
are conducted or transmitted from one point to another. 

ELECTRO - MOTIVE FORCE.— The attribute of 
electrical energy manifested in the force of the current 
from one point to another along a path or conductor, and 
may be used as a motive power for doing work. 

POTENTIAL.— As ordinarily used, signifies the 
amount of change from the normal state, from one point 
in relation to another in the same system. It has a rela- 
tive meaning and expresses the difference in electrical 
power or level of one point in relation to another. 

VOLT. — The measure of the difference in electrical 
potential. AVhen any two points in a circuit differ in 
potential, there is a tendency for them to return to a 
normal state or equal potential. This tendency is repre- 
sented by electro-motive force, the unit of which is 
called a volt. 

CONDUCTOR,— The medium or path through which 
electric energy or its effects may be transmitted from 
one point to another. Conductivity represents the degree 
or capacity which any substance or path provides for the 
passage of the electrical current. Silver, copper and 



156 ELECTRICITY. 

metals generally are good conductors, over or through 
which the current flows easily; while rubber, glass, 
slate, etc., are poor conductors. 

INSULATOR. — A very poor conductor, or non-con- 
ductor of electricity. 

OHM. — The unit of measure of resistance. For 
example, one hundred feet of No. 20, B. & S. copper 
wire lias a resistance of about one ohm. 

AMPERE. — Unit of measure, of the rate of flow, or 
velocity of the electric current. 

CIRCUIT. — The entire circle or path through which a 
current travels. 

OPEN CIRCUIT,— When at any point there is an 
insulator over which but a small current can pass. 

A SHORT CIRCUIT.— When the current is diverted 
from its course, a path being opened having lower 
resistance than the one intended for it to travel in. 
When such a short cut is provided, a large part of the 
current may be diverted from its regular path and may 
prove a source of danger, by heating and firing the 
conductor by which the current is diverted. 

CLOSED CIRCUIT.— When a circuit, by the use of 
good conductors, is complete in every part. Cutting a 
wire over which the current is passing, so that there is 
only air between their ends, opens the circuit, as then 
but a small current of electricity can pass. 

INDUCTION. — Effects manifested in a secondary wire 
without any metallic connection, when the current in the 
primary wire varies in strength, owing to the near 
presence of another current or wire conductor. 

RESISTANCE.— The property of a body, the tendency 
of which is to interfere or resist the flow of the current : 
and through which more energy is required to force the 
current through. Insulators have great resistance. 



ELECTRICITY. 157 

HIGH RESISTANCE.— Any material which presents 
great obstruction to the passage of a current, may be 
said to have high resistance. In a circuit composed of 
obstructions, such as a series of lamps, the resistance is 
comparatively high. 

LOW RESISTANCE.— Other things being equal, every 
additional wire for the current proportionally reduces 
the resistance. The more the resistance between any 
two points is reduced, the more current can be made to 
flow through the circuit, with a given E.M.E. If the 
resistance of one wire be 40 ohms, the arranging of 
another wire parallel with the lirst, of the same re- 
sistance in itself, will make the joint resistance of the 
two wires half that of one, or 20 ohms; if four wires, 
with a resistance of 40 ohms each, the resistance of the 
whole system of the four wires will be reduced to one- 
quarter of the one, or 10 ohms. 

ILLUSTRATION.— If there are 5 lamps in a circuit, 
each offering a resistance of ± ohms, requiring a pressure 
of 50 volts to force the current through one lamp : these 
lamps being connected in a series, would offer a mutual 
resistance of 5 times 4, or 20 ohms ; and to force the 
current through these 20 ohms, would require an electric 
motive power five times as strong as the one lamp, or 
250 volts. 

MULTIPLE ARC. — Apparatus arranged to operate 
a series of arc lights and so regulated as to deliver a 
current of constant strength proportional to the re- 
sistance of the circuit, the resistance varying with the 
number of lamps in operation. The apparatus being 
connected in multiple arc, as a rule, is of low resistance : 
for the more paths or wires by which the current can go 
from one point to another, the lower the resistance of 
the whole circuit. 



158 ELECTRICITY. 

INCANDESCENT LAMP.— Consists mainly of a 
filament of carbon, or other refractory substance, en- 
closed in an air -tight glass globe. The carbon filament 
is supported within the glass bulb by two terminal wires. 
generally of platinum, and the carbon may be of various 
form and size, proportional to the current it is to carry 
and the amount of light it is designed to furnish. The 
wires extend through the glass, and on the outside 
means are provided for making electrical connection 
with the carbon filament within. 

ARC LAMP. — Is an apparatus for producing light by 
means of the voltaic arc. It consists of a mechanical 
device for holding two carbon pencils in a vertical line, 
one above the other, a small distance apart. The lower 
carbon is usually fixed and the upper one movable, and 
so adjusted that by means of electro magnets its move- 
ment is controlled by the current circulating through 
the lamp, so that the points of the carbon are kept a 
small distance apart. 

INCANDESCENT LIGHTING.— The lamps are usually 
connected in multiple arc or parallel paths. If one lamp, 
having a resistance of 100 ohms, requires an E.M.F. of 
100 volts to force one ampere of current through it, then 
with live lamps connected, the resistance of the system 
will be reduced to *~ that of the one, or 20 ohms. The 
net resistance being reduced to 20 ohms, the E.M.F. of 
100 volts will force five times as much current over the 
circuit as in the first case, or 5 amperes. As each lamp 
requires one ampere, the total current going over the 
several wires is just enough for the five lamps. Hence 
for incandescent lighting, a dynamo will be required that 
will keep the current at a constant pressure, and supply 
more current as the resistance of the external circuit is 
lowered by the addition or opening of other lamps. 



ELECTRICITY. 159 

ALTERNATOR.— A mechanical device providing 
means for shifting the current or changing the alter- 
nating current of the arc lamp to incandescent lamps. 
An apparatus provided for running either arc or incan- 
descent lamps on the same circuit with same dynamo. 



PARTS OF THE DYNAMO. 

DYNAMO. — A machine for converting mechanical 
energy into electrical energy, consisting essentially of 
magnets mounted on a solid base and an armature and 
other parts so arranged as to rotate rapidly between the 
magnets. 

ARMATURE. — The central point wherein the me- 
chanical energy is transmitted to the pulley or drum, and 
converted into electrical energy. It usually consists of 
coils of wire wound upon a suitable frame- work, com- 
posed of many pieces, insulated each from the other, and 
all mounted on a shaft, capable of rapid revolution. 

MULTIPOLAR ARMATURE.— Is made up with 
several soft iron cores wound with insulated wire, in 
which the 

COMMUTATOR — Is composed of copper strips 
thoroughly insulated and mounted on a 

SPOOL,— Placed on the same shaft as the armature. 
These armatures present a broken surface and are 
generally used in so-called alternating machines. 

RING ARMATURES.— Have an air space between 
the hub and ring, and their diameter usually exceeds 
their length. They require a device called a 



160 ELECTRICITY. 

SPIDER. — Hub and spokes of non-magnetic metal, 
used in connection with rings of insulated iron wire in 
making up an armature of the Gramme type. 

DRUM ARMATURES.— Do not require a spider, and 
their length usually exceeds their diameter. 

POLE PIECES, YOKES OR BACK STRAPS.— The 
parts directly facing the armature and the parts by 
which the cores are fastened together or to the frame of 
the machine. 

CORES. — The frame work on which coils of wire are 
wound, usually made of soft iron disks on a shaft and 
insulated by some thin non-magnetic substance. 

FIELD MAGNETS.— Large iron pieces, wound with 
insulated copper wire, between the ends of which the 
armature rotates. 

BRUSHES. — Bundles of wires or strips of copper 
springs, in contact with and bearing diametrically on 
the opposite sides of commutator. They assist in con- 
ducting the current to the external circuit. 

POLES OR FIELD OF FORCE.— The central point 
of a powerful attraction between the ends of magnets, 
as illustrated by placing iron or steel near these 
magnets. Field of force, the radius of this invisable 
power of attraction for metals, in which, if coils of wire 
are rotated rapidly, an electrical current is generated, 
which lasts only while the motion continues. 

MAGNETIC FRICTION.— A peculiar friction, which 
acts like a brake on the armature, when in motion. 
By the continuous motion of the armature in over- 
coming this friction, the current is generated in the 
coils of wire. The essential work of the dynamo is to 
pull the armature around against this friction (or back- 
ward te idency) by means of the mechanical energy 
applied to the dynamo. 



ELECTRICITY. 161 



RELATION BETWEEN CURRENT RESISTANCE 
AND ELECTRO-MOTIVE FORCE. 

Certain relations exist between the resistance of a 
circuit, the current flowing through it, and the electro- 
motive force that drives the current through the circuit. 
The resistance of a circuit and the E.M.E. under which 
the electric current is flowing, being known, the value of 
the current in amperes may be determined by dividing 
the number which expresses the E.M.F. (in volts), by 
the number that expresses the resistance (in ohms). 
Thus : the E.M.F. as between the points of a circuit (as 
found by a volt meter) being 80 volts, the resistance 
between the same points being 20 ohms — 20) ^ amperes. 
Again, the resistance of any wire or part of a circuit 
being known, to find the E.M.E. required to drive a 
certain strength through this wire, multiply the number 
expressing the current in amperes by the number express- 
ing the resistance of wire in ohms, and we have the 

number of volts. Thus : Resistance 20 ohms 
Amperes 4_ 

80 volts. 

Again, to find the resistance of a part of a conductor 
between two points, knowing the electro-motive force, di- 
vide the volts by the number of amperes, which expresses 
the strength of current, and we have the resistance in 

Ohms. Thus: 4)P0 volts, E. M. F. 

20 ohms, resistance. 

The well-known formula by which these relations may 
be stated is : C. representing amperes ; E, the numbeivof 
volts ; R, the number of ohms. Expressed. c=|. In these 
formulae the number above the line is always to be divided 
by the number below the line. 



li 



162 ELECTRICITY. 

For example : desiring to know the value of current in 
amperes: formula (1), c=~- 

If we desire the value of E.M.F. in volts: formula 
(2), E=CXR. 

When the resistance is required in ohms : formula (3), 

R =c- 

By the understanding of these formulas, many practical 

questions may be easily solved. For example: it is de- 
sired to know the resistance in a group of incandescent 
lamps when hot, in multiple arc. An ammeter placed in 
the circuit shows a reading of 10 amperes. The volt- 
meter, with one terminal connected with the wire leading 
to the group and the other terminal connected with the 
wire leading from the group, shows a reading of 80 volts. 
Referring to formula (3) for finding resistance: R=j|. 
E and C are known, 11 we wish to find : r= ~. =8 . The resist- 
ance of the group when hot, then, is 8 ohms. 

If there were 10 lamps in the group, and we want to 
know the resistance of one lamp hot ; then, as the net 
resistance of the 10 lamps united in multiple arc would be 
yV that of one, the resistance of one lamp hot in this case is 
10X8 or 80 ohms, and the resistance of the lamp cold would 
be about twice as much as when hot, or 160 ohms. To solve 
the same problem by direct measurements would involve 
the use of expensive instruments, perhaps not available. 

Again : If 25 arc lamps, hung in a series, require an 
8-ampere current, and the maker has given their resist- 
ance (when burning) as I ohms each, and the circuit in 
which they are hung is made of No. 6 B. & S. wire and is 
two miles long ; then (ignoring the resistance of the 
dynamo) , we find — by reference to the following table — ■■ 
that two miles of No. 6 wire has a resistance of about 
4 ohms (if the joints are as they should be). There- 
fore, 25 lamps, each i ohms, would be 100 ohms; this, 
plus the resistance of the circuit, would be about 101 



ELECTRICITY. 



163 



ohms. Now, referring to the formula for finding E.M.F. 
(2). ^e know C and R; CXR or 8X104=832 E. That 
is, the E.M.F. at the terminals of dynamo would be 
about 832 volts. By direct methods special and costly 
volt-meters would be required. 



RESISTANCE AND SAFE CURRENT OF WIRES. 



No. B. & S. Resistance, 1,000 ft. Safe Current. 



1 

WIRE. 


OHMS. 


AMPERES. 


1 


.12 


127 


2 


.15 


101 


O 


.19 


80 


4 


.24 


63 


5 


.30 


50 


6 . 


.39 


40 


7 


.49 


32 


•8 


.61 


25 


9 


.77 


20 


10 


.98 


15 


12 


1.5 


10 


14 


2.5 


6 


16 


4. ' 


4 


18 


6.3 


3 


20 


10. 


2 



These formula? and table are useful in laying out 
wire for incandescent lamps, etc. 

Forcing the current over a line means overcoming 
resistance, and as a certain amount of electro-motive 
force is disposed of in this way, it becomes of consider- 
able importance to so proportion the wires as to get the 
least loss consistent with conductors of reasonable price. 

A careful study of the above will familiarize the mind 
with knowledge which may be usefully applied in electrical 
works generally. 



164 



MISCELLANEOUS WEIGHTS AND MEASURES. 

A point = 7V of an inch. 

A line = 6 points = (-^ of an inch.) 

A palm = 3 inches. 

A hand = 4 inches. 

A span = 9 inches. 

A link=7.92 inches. 

A chain = 100 links = 66 feet = 4 rods. 

A fathom = 6 feet. 

A nautical mile = 6,086 feet and f, nearly. 

A barrel of flour = 196 pounds. 

A barrel of cement = 300 pounds. 

A ton of anthracite coal (broken) = 42 cubic feet. 

A ton of bituminous coal = 47 cubic feet. 

A stone =14 pounds. 

A load of lime = 32 bushels. 

A load of sand = 36 bushels. 

A cable's length = 126 fathoms = 720 feet. 

An acre= 10 square chains. 

A load of bricks = 500 in number. 

A cord of wood = 128 cubic feet. 

A cord foot = 4 ft. long x 4 ft. high, 1 ft. wide. 

A cord = 8 corcl feet. 

A load of unhewn timber = 40 cubic feet. 

A load of squared timber = 50 cubic feet. 

A load of inch boards = 60 square feet. 

A load of 2-inch planks = 300 sq. feet. 

A cubic foot of tallow = 59 pounds. 

A hundred of nails = 120 in number. 

A thousand of nails = 1,200 in number. 

A bushel of sand= 123 pounds 

A bushel of lime = 85 pounds. 

A ton of coke = 95 cubic feet. 



165 



WEIGHT OF WATER. 



Water. 


Pounds. 


1 cubic in 


.03627 


12 " " 


.434 


1 " ft. (salt).... 
1 " " (fresh).. 
1.8 " ^ " .. 
35.84 cub. ft. " .. 

1 cylindrical in 

12 » 

1 " ft 

2.282 " 

45.64 " " .... 


64.3 
62.5 
112. 
2240. 

.02842 
.341 
49.10 
112. 
2240. 


U. S. Gallons. 




1 XT. S. gallon 

13.44 U. S. gallons. 
268.8 " ' " . 


8.355 
112. 
2240. 


Imperial Gallons. 




1 Imperial gallon.. 
11.2 " gallons. 
224 " ■ " . 


10. 
112. 

2240. 



1 cubic ft. water=7.48052 U.S. gals. 
1 cylindrical ft. water=6 U.S. gals. 



Note. — The center of pressure of 
a body of water is at two-thirds the 
depth from the surface. 

To find the pressure in pounds per 
sq. in. of a column of water, multi- 
ply the length of the column in feet 
by 434. Every foot elevation is con- 
sidered (approximately) equal to 
one-half pound pressure per. sq. in. 



Steam. 

Steam is an elastic fluid, generated by the action of 
heat upon water. 

Steam, when separated from the water from which it 
is generated, follows the law of all other gases, expand- 
ing 1,459 of its volume for each additional degree of heat, 
while the pressure remains the same. 

The temperature of steam is equal to that of the water 
from which it is formed, and its elasticity is equal to the 
pressure under which it is formed. 

Total heat of steam at 212° is 1,178. 



166 



TABLES. 



HEAT UNITS IN WATER, BETWEEN 32° AND 212° 
AND WEIGHT OF WATER PER CUBIC FOOT. 



to 

u 

S3 


OD 


PC 


6 


EC 


P O 


6 


i 


5.2 








o 






* 






53 


fl 


""lla 


q 


...a 




"~3 


s 




3 - 






© 


~ 




B 


C3 






C3 


"6 S 


En 


r; 


© 3 


32°F 


0. 


62.42 


123° F 


91.16 


61.68 


168°F 


136.44 


60.81 


35 


3. 


62.42 


124 


92.17 


61.67 


169 


137.45 


60.79 


40 


8. 


62.42 


125 


93 17 


61.65 


170 


13S.45 


60.77 


45 


13. 


62.42 


126 


94.17 


61.63 


171 


139.46 


60.75 


50 


18. 


62.41 


127 


95.18 


61.61 


172 


140.47 


60.73 


52 


20. 


62.40 


128 


96.18 


61.60 * 


173 


141.48 


60.70 


54 


22.01 


62.40 


129 


97.19 


61.58 


174 


142.49 


60.68 


56 


24.01 


62.39 


130 


98.19 


61.56 


175 


143.50 


60.66 


58 


26.01 


62.38 


131 


99.20 


61.54 


176 


144.51 


60.64 


60 


28.01 


62.37 


132 


100.20 


61.52 


177 


145.52 


60.62 


62 


30.01 


62.36 


133 


101.21 


61.51 


178 


146.52 


60.59 


64 


32.01 


62.35 


134 


102.21 


61.49 


179 


147.53 


60.57 


66 


34.02 


62.34 


135 


103.22 


61.47 


180 


148.54 


60.55 


68 


36.02 


62.33 


136 


104.22 


61.45 


181 


149.55 


60.53 


70 


38.02 


62.31 


137 


105.23 


61.43 


182 


150.56 


60.50 


72 


40.02 


62.30 


138 


106.23 


61.41 ' 


183 


151.57 


60.48 


74 


42.03 


62.28 


139 


107.24 


61.39 


184 


152.58 


60.46 


76 


44.03 


62.27 


140 


108.25 


61.37 


185 


153.59 


60.44 


78 


46.03 


62,25 


141 


109.25 


61.36 


186 


154.60 


60.41 


80 


48.04 


62.23 


142 


110.26 


61.34 


187 


155.61 


60.39 


82 


50.04 


62.21 


143 


111.26 


61.32 


188 


156.62 


60.37 


84 


52.04 


62.19 


144 


112.27 


61.30 


189 


157.63 


60.34 


86 


54-05 


62.17 


145 


113.28 


61.28 


190 


158.64 


60.32 


88 


56.05 


62.15 


146 


114.2S 


61.26 


191 


159.65 


60.29 


90 


58.06 


62.13 


147 


115.29 


61.24 


192 


160.67 


60.27 


92 


60.06 


62.11 


148 


116.29 


61.22 


193 


161.68 


00.25 


94 


62.06 


62.09 


149 


117.30 


61.20 


194 


162.69 


60.22 


96 


64.07 


62.07 


150 


118.31 


61.18 


195 


163.70 


60.20 


98 


66.07 


62.05 


151 


119.31 


61.16 


196 


164.71 


60.17 


100 


68.08 


62.02 


152 


120.32 


61.14 


197 


165.72 


60.15 


102 


70.09 


62.00 


153 


121.33 


61.12 


198 


160.73 


60.12 


104 


72.09 


61.97 


154 


122.33 


61.10 


199 


167.74 


60 10 


106 


74.10 


61.95 


155 


123.34 


61.08 


200 


168.75 


60.07 


108 * 


76.10 


61.92 


156 


124.35 


61.06 


201 


169.77 


60.05 


110 


78.11 


61.89 


157 


125.35 


61.04 


202 


170.78 


60.02 


112 


80.12 


61.86 


158 


126.36 


61.02 


203 


171.79 


60.00 


114 


82;13 


61.83 


159 


127.37 


61.00 


204 


172.80 


59.97 


115 


83.13 


61.82 


160 


128.37 


60.98 


205 


-173.81 


59.95 


116 


84.13 


61-80 


161 


129.38 


60.96 


206 


174.83 


59.92 


117 


85.14 


61.78 


162 


130.39 


60.94 


207 


175.84 


59.89 


118 


86.14 


61.77 


163 


131.40 


60.92 


208 


176.85 


59.87 


119 


87.15 


61.75 


164 


132.41 


60.90 


209 


177.S6 


59.84 


120 


88.15 


61.74 


165 


133.41 


00.87 


210 


178.87 


59.82 


121 


89.15 


61.72 


166 


134.42 


69.85 


211 


179.89 


59.79 


122 


90.16 


61.70 


167 


135.43. 


60.83 


212 


180.90 


59.76 



TABLES. 



167 



Total Heat Evolved by Combustibles, and their Equivalent 
Evaporative Power, with the Weight of Oxygen and 
Quantity of Air Chemically Consumed. 



Kind of Combustible. 



Hydrogen 

Carbon, making Carb. Oxide.. 
" Carbonic Acid.. 

Carbonic Oxide 

Light Carbonated Hydrogen.. 
Bi-Carb'ted Hydrogen 01. Gas 

Sulphur . 

Coal, average composition.. . . 

Coke, dessicated 

Wood 

Peat 

Lignite 

Asphalt 

StraAV, 12| % moisture. 

Petroleum 



Ph 



8.0 

1.33 

2.66 

.57 
4.0 
3.43 
1.00 
2.46 
2.50 
1.40 
1.75 
2.03 
2.73 

.98 
4.12 






34.8 
5.8 

11.6 
2.48 

17.4 

15.0 
4.35 

10.7 

10.9 
6.1 
7.6 
8.85 

11.87 
4.26 

17.93 



o^3 

Q 



457 

76 
152 

33 
229 
196 

57 
140 
143 

80 
100 
116 
156 

56 
235 



o 



So 
so 
P 



60.032 

4.452 

14.500 

4.325 

23.513 

21.343 

4.032 

14.133 

13.550 

7.792 

9.951 

11.678 

16.655 

5.196 

27.531 



© j. © 

> <- u 
•« s © 

£<§£ 

loo 

C O ©fa 



64.2 

4.61 
15.0 

4.48 
24.34 
22.00 

4.17 
14.62 
14.02 

8.07 
10.30 
12.10 
17.24 

5.56 
28.50 



Combustion of Fuel 



Is the result of a chemical union of carbon and oxygen. 
Perfect results require about 2% lbs. of oxygen to 1 lb. 
of carbon, properly mixed. 

The fireman should understand this law and aim to 
supply the necessary amount of oxygen and secure the 
proper mixture. 



168 



TABLES. 



PROPORTIONS OF CYLINDRICAL TUBULAR BOILERS. 









Tubes. 






© 


Stack. 


£ 












PH 


•d 


© 




% 


. 










© 


02 © 






o 

© 
w 


© 




^ 


© 




%m 


COM 
<U HI 


53 


© 




.4 
bo 


1 


© 

g 


+3 


© 


P 

© 




© 

B 


+3 

bJO 


?M 


a 





aS 


£ 






fl 


3 




o 




© 






© 


2 


2 


© 




© 


M 


s 


J 


fc 


s 


^ 


H 


H 


Kl 


S 


Pu 




In. 


Ft. In. 




In. 


Ft. 


In. 


In. 


Ft. 


In. 


Ft. 


15 


36 


8 11 


30 


3 


8 


i 

3 


1 


3 


18 


26 


20 


36 


10 11 


30 


3 


10 


l 
4 


1 


3^ 


18 


30 


25 


42 


11 


38 


3 


10 


3% 


I 


3| 


20 


30 


30 


42 


13 


38 


3 


12 


A 


1 


4 


20 


36 


35 


44 


13 


46 


3 


12 


ft 


1 - 


4 


22 


36 


40 


48 


13 2 


52 


3 


12 


ft 


1 


4 


24 


36 


45 


50 


14 2 


52 


3 


13 


ft 


§ 


4 


24 


36 


50 


54 


13 2 


58 


3 


12 


T 5 6 


i 


4 


26 


36 


60 


54 


16 2 


58 


3 


15 


ft 


1 


4| 


26 


45 


70 


60 


16 4 


76 


3 


14 


tf 


ft 


4* 


28 


45 


75 


60 


16 4 


76 


3 


15 


ft* 


ft 


4i 


28 


50 


80 


60 


17 4 


76 


3 


16 


tt 


ft 


5 


28 


55 


90 


66 


16 5 


100 


3 


15 


f 


ft 


5 


32 


55 


100 


66 


17 5 


100 


3 


16 


1 


ft 


5 


32 


55 


125 


72 


17 6 


132 


3 


16 


ft 


1 


5 


36 


60 



The Construction of Boilers 
Varies with conditions. The plain cylindrical and the flue 
boiler are used when the cost of fuel is low and the feed 
water is poor, with limited opportunities for repairs. 
The multitubular boiler is more complicated, but it is 
more economical aucl is the kind in general use. In 
the return tubular boiler, 15 square feet of heating surface 
is usually allowed for each horse-power. The ratio of 
heating to grate surface with stationary or "dead" bars 
is about 40 heating surface to 1 grate surface ; with a 
good shaking grate, about 50 to 1 of grate surface. 



TABLES. 



169 



03 © 



op 



* II 

CO 03 03 

S ® © "8 

is Hi 

CO g g <1 

§ &&§ 

u. gg ^ 

* if I 

3 « d 



© © 

-03 

1 

I* 



No. of 
Threads 
per In. of 

Screw. 


l-fcji-lfNHjN'-** 

t^OOOO-^r^^-iiHT-i^HOCOOCOCOCOCOOOOOOOOOQO 

(Mr-HHHrlHHrl 


Weight 

per Foot of 

Length. 


Hi 


MNiHiSOCOO^NeOb-lOaON^t^OCQh-H 
"THrHCN^cOiO^ciOcN^OOCOOOrlHO 


Length of 
Pipe, con- 
taining one 
Cubic Foot. 


£ 


UOLOCDHCIC-HMOOO^XOO 
^ lO "* ^MOCOH^lCCOCCMCit^XNCiO 
ClCHMOC0C0CWOC:'*H03t>'+MNCNri 
OCOLOt^l>OOt-'*WHrlH 
K3 CO t- Tt< CM tH 
<M rH 


External 
Area. 


d 


CCM"*Cl'- , *iOOTHrHO^»CC5--M<OL'5CM 
CN<MOi£>:OiCOOCOCOCiC>ciOOCOCll^«£<N'-tCi 
THC^COiOCOC^rHQOT^Tt;COlCC^CiC^r^OrfJt>-l>- 

'riW00^ddcNdC5'*'*KJ^c6d 
iHi-iT-KMCOrfiiCb-c: 




d 


CM H CD X CO t- 

l^^^^CCCNOXlOCOCONOOlOOlb-acOOO 
IC O Ci O CO ^i C CO LO X X CO CO C* Oi 00 CO CO CO CO 
G^THeOlOCO^OCOb-COOOb-CiCSaOt^O^DOO 

"^oico^t^cioqiocioocoocooo 

HH^-KNCOlOCt- 


S ^4i © 




UO N CM N CO CO HaHUOClOOt-lO^^lO 
^l^iOOMOCnHMOiC-fCD(Mt-OT(*CSiO 

^oowo^coqocooaccbjCioioijMco 

cit^»O^COc4cMCcirHr^rH 


External 

Circum- 
ference. 


M 


C^CO^CMCi^iCO-^CMCOCOI^OOlCCOTtiCCCOOq 

h-QCNlOOiCOHOCCOOCCOCt-'-iOOlCOt" 

iHrHCMC^COrJHid^t^oioci^i^L^OCOlr^OCO 

HHHrHHCNCNCNCOCO 


Actual 
Outside 
Diam. 


O 1Q O lO iro CO 1C ^ lO X 

_; O^NCL'HO t-t- CO M M ^1 00 O 

S ! rj^LOCxqcoccicoxLO y: _ io «© co o o t-; 

' H H H H N CN M Tj5 rjH O IC ffl t^ 00 C5 O 


Inside 
Diam. 


fl 


iHH-CNCNWCO^Tt"OOt-XOO 



170 



TABLES. 



6 0; h § o 



Ttt^OHCit-t-t-NNMCXCM-CXr-O'tW 



^5S 
k © c 



fl £ © O +J 

© g fl'+H CO 



O 050MI>r-iCCO tH CO CO CO CO OJ CM CTi t~- U5 

t- HcoiooflDosoiNeo^iocot-oo© Or-icsi 

wicoNMcnoHm^oot"Xco-:o'f ice 

OOOOOOHHHHHHHrinNNMNNN 



© © o ■ 
— ° fi OS 



CO ffl OS -H OS CO lO iq -* rH fcr; ff» «>; © CO lO t~ OS OS 00 

CO iH rH 00 © CO* iC C^ OS rH 0^' rH »C t-^ OC OS ©* tH c4 rt< 1Q 
rH lO lO lO SO CO »©©t-Nt-t-t-t't- X MXXX 



c8 sw 

CD O • 

rfl ©2- P 

rt'd p 

■S o el £ 

— — — ■ 

cti ft 



I PI 



NOf0CliC00O>Ol0'*O)rtt>^^^OC-rOL0 



© % co 3 o 

n s s M £a 
P h o ® s » 



.91 



H cS+ i o> 



© — • 72 Jh +» 



S i Q 



oJ i4 os os 00 co rtf o «> c*t^ cq 1* *h co © co bj rJ r* tj 

— oq co rH ic ■ "-C b- X oc ■ 0: 01 © o — — oi 04 01 co co co 

CNOqCN^CNOlfNOlCNCSC^COCOCOCOCOCOCOCOCOCO 



CD 








tn 




















(H 


~ 


CD 
CD 


p- 


fl 


O lO O lO 


O lO 


~1COOO 


S 


010c 


Iffl 


10 


g 

PL, 


- 


30 


cd 
CJD 




DC 




OS! CM CO CO rH rH lO 


»©t-t"»X 


© Ot © 



TABLES. 



171 



— 
o 

P 

H 

P-i 
H 

< 



b 

CO 


■^ :: o co 1 
cs os os co | 
—i* co >o t- 


b 

to 


t-i cni re "* © 

© CO t- (£> lO 


© 


oo t^ «£> »q co csi 

rH co »o t^ OS «H 


b 


•*t-M«OOlOOO 

co to »q co (N © co 

iH « 1Q t^ OS i-H tH 


I 


C h (N « W >t ic O 
r-KCOldt^CSOC^riH 


b 


©GOt-JOOO-fCOCSI 

©ca^^ococsrHCOiQ 

r-liHiH 


b 

GO 


ooN-Nionot- 
rH CO «6 *- CO o c4 rH »c 


g 


COCO^i-jOSCO^-HOSt-; 

d cn ■* © l- —' — :-! — d 


co 


*©WN(N©OOO^I 

■^ "t ^ r : '" * ^ * "^ ^ 


b 


dei^cob^o^rH.corPcoco 


b 


HM^LONXOHM^lO 
f-rJJ t-j CO lO CN O t^ ■«* ; tH CO 

THeoiodcodoirodt^co 


(N 

CO 


C»OSOSOQO'OOOOSO 

coOfc-»qc4os<ocoob^'«*j 



•jajioq m 
paj'naqAv 



c3 cc - 
if. - ^ 



ED 


'— 


r: 






— 


:/. 


£j 




tu 






~ 


+a 


S3 


^, 


fl 


- 






es ^ 






— 


£ 




D 


7, 






- 

i 

w 




EC 


- 




n 






7. 






'— 


3 


p, 


U 


— 

c 

2 


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172 TABLES. 

DIAMETER, CIRCUMFERENCE AND AREA OF CIRCLES. 



Diameter. 


Area. 


Circum- 
ference. 


Diam. 


Area. 


Circum- 
ference. 


In. 


In. 


In. 


In. 


In. 


In. 


1 


.012 


.3926 


12 


113.69 


37.69 


i 

4 


.049 


.7854 


m 


122.71 


39.27 


| 


.110 


1.178 


13 


132.73 


40.84 


1 
2 


.196 


1.570 


13| 


143.13 


42.41 


5. 


.307 


1.963 


14 


153.93 


43.98 


I 


.442 


2.356 


141 


165.13 


45.55 


| 


.601 


2.748 


15 


176.71 


47.12 


1 


.785 


3.141 


16 


201.06 


50.26 


11 


1.227 


3.927 


17 


226.98 


53.40 


H 


1.767 


4.712 


18 


254.46 


56.54 


11 


2.405 


5.497 


19 


' 283.52 


59.69 


2 


3.14 


6.283 


20 


334.16 


62.83 


2i 


3.97 


7.068 


21 


346.36 


65.97 


2* 


4.90 


7.854 


22 


380.13 


69.11 


2f 


5.03 


8.639 


23 


415.47 


72.25 


3 


7.06 


9.424 


24 


452.39 


75.39 


3$ 


8.29 


10.21 


30 


706.86 


94.24 


3| 


9.62 


10.99 


36 


1016.88 


113.0 


3| 


11.04 


11.78 


42 


1385.4 


131.9 


4 


12.56 


12.56 


48 


1809.6 


150.7 


4| 


15.90 


14.13 


50 


1963.5 


157.0 


5 


19.63 


15.70 


52 


2123.7 


163.3 


5ft 


23.75 


17.27 


54 


2290.2 


169.6 


6 


28.27 


18.84 


55 


2375.8 


172.7 


6§ 


33.18 


20.42 


56 


2463.0 


175.9 


f 


38.48 


21.99 


60 




188.4 


n 


44.17 


23.56 


62 




194.7 


8 


50.26 


25.13 


64 




201.0 


Sh 


56.74 


26.70 


72 




226.9 


9" 


63.61 


28.27 








9i 


70.88 


29.84 








10 


78.54 


31.41 








J0| 


86.59 


32.98 








11" 


95.03 


34.55 








m 


103.86 


36.12 









To Determine Height of Chimney. 
The area being known, also the rate of combustion, 
multiply the number of pounds of coal consumed under 
the boiler per hour by 12 and divide the product by the 
sectional area of the chimney in square inches : square 
the quotient thus obtained, which will give the proper 
height of the chimney in feet. 



TABLES. 



173 



WEIGHT AND VOLUME OF CAST IRON AND LEAD BALLS 
From 1 to 20 in. 



Diam. 


Volume. 


Cast Iron. 


Lead. 


In. 


Cubic In. 


Lbs. 


Lbs. 


1 


.5235 


.1365 


.2147 


1 -., 


1.7671 


.4607 


.7248 


o 


4.1887 


1.092 


1.718 


- 2 


8.1812 


2.1323 


3.3554 


3 


11.1371 


3.6855 


5.7982 


Z% 


22.4192 


5.8525 


9.2073 


4 


33.5103 


8.7361 


13.744 


±k 


47.7129 


12.4387 


19.569 


5 


65.4498 


17.0628 


26.843 


5>£ 


87.1137 


22,7206 


35.729 


6 


113.0973 


29.4845 


46.385 


1% 


143.7932 


37.4528 


58.976 




179.5943 


46.8203 


73.659 


1% 


220.8932 


57.587 


90.598 


8 


268.0825 


69.8892 


109.952 


s* 2 


321.555 


83.8396 


131.883 


9 


381.7034 


99.5103 


156.553 


9K 


448.9204 


117.0338 


184.121 


10 


523.5987 


136.5025 


214.749 


11 


696.9098 


1S1.7648 


285.832 


12 


904.7784 


235.8763 


371.806 


13 


1150.346 


299.623 


471.806 


14 


1436.754 


374.5629 


589.273 


15 


1767.145 


460.6959 


724.781 


16 


2144.66 


559.1142 


879.616 


17 


2572.44 


670.7168 


1055.066 


IS 


3053.627 


796.0825 


1252.422 


19 


3591.363 


936.2708 


1472.97 


20 


4188.79 


1092.02 


1717.995 



To Find the Weight of Safety Valve 

Required to balance a given pressure at a given distance 
from the fulcrum : — 

Multiply the area of the valve by the pressure, and 
from the product subtract the weight of the valve and 
lever. Multiply the remainder by the distance cf the 
stem from fulcrum and divide by distance of ball from ful- 
crum; the quotient will be the required weight in pounds. 



174 



TABLES. 





WEIGHT OF IRON. 


Size. 


Round Iron. 


• 
Square Iron. 


In. 


Lbs. 


Lbs. 


ft 


.118 


.117 


i 


.163 


.208 


ft 


.257 


.325 




.368 


.468 


7_ 


.501 


.638 


I 


.654 


.838 


_9_ 


.833 


1.01 


g 


1.02 


1.30 


3 


1.47 


1.87 




2.00 


2.55 




2.61 


3.33 


11 


3.31 


4.21 


11 


4.09 


5.20 


1| 


5.94 


6.30 


1* 


6.89 


7.50 


1^ 


7.91 


8.80 


If 


8.01 


10.20 




9.02 


11.71 


2 


10.47 


13.33 


2 ir 


11.82 


15.05 


2i 


13.25 


16.87 


2| 


14.76 


18.80 


2^ 


16.36 


20.80 


2 s 


18.03 


22.96 


2| 


19.79 


25.20 


92 


21.63 


27.55 


3 


23.56 


30.00 



PLATE IRON. 


Thick- 


Weight per 


ness. 


Square Foot. 


In. 


Lbs. 


i 


2.55 


Jl 


5.03 


ft 


7.56 


1 
, 3 


10.07 


ft 


12.59 


6 
8 


15.11 


ft 


17.62 


h 


20.14 


JL 


22.66 


f 


25.18 


II 


27.69 


1 


30.21 


M 


32.73 


1 


35.25 


15 


37.76 


1 


40.28 


n 


45.32 


n 


50.35 


if 


55.39 


n 


60.42 


if 


65.46 


it 


70.49 


n 


75.53 


2 


80.56 



Strength of Boiler Plates. 

The tensile strength of American boiler iron is 40,000 
to 60,000 lbs. per square inch. Very high tensile strength 
in boiler iron is apt to lack homogeneousness and tough- 
ness. Toughness of boiler plate iron better stands irreg- 
ular strains and shocks. 



umhSj of congress 

029 822 385 5 



